Wind power generation device

ABSTRACT

A one-way clutch used in a wind power generation device integrally rotatably connects an input rotating body and an output rotating body to each other in a state in which a rotational speed of the input rotating body exceeds a rotational speed of the output rotating body, and breaks connection between the input rotating body and the output rotating body in a state in which the rotational speed of the input rotating body is lower than the rotational speed of the output rotating body. The input rotating body and the output rotating body are allowed to relatively move along an axial direction, and a maximum allowance of movement is set to be larger than variation of a distance along the axial direction between an input shaft and an output shaft caused by state change.

TECHNICAL FIELD

One aspect of the present invention relates to a wind power generationdevice in which a power generator is driven by increasing, by a speed-upgear, the speed of rotation of a main shaft caused by, for example, awind force.

BACKGROUND ART

As an example of a wind power generation device of the background art, awind force is received by a blade to rotate a main shaft connected tothe blade, and a speed-up gear is used for increasing the speed of therotation of the main shaft to drive a power generator. As illustrated inFIG. 23, such a speed-up gear 202 includes a planetary gear mechanism203 that receives the rotation of a main shaft 200 to increase itsspeed; a high-speed stage gear mechanism 204 that receives the rotationincreased in speed by the planetary gear mechanism 203 to furtherincrease its speed; and an output shaft 205 outputting the runningtorque of the high-speed stage gear mechanism 204.

In the planetary gear mechanism 203, when an input shaft 203 aintegrally rotatably connected to the main shaft 200 is rotated, aplanetary carrier 203 b is rotated to rotate a sun gear 203 d at anincreasing speed via a planetary gear 203 c, so that the rotation of thesun gear can be transmitted to a low-speed shaft 204 a of the high-speedstage gear mechanism 204.

In the high-speed stage gear mechanism 204, when the low-speed shaft 204a is rotated, an intermediate shaft 204 d is rotated at an increasingspeed via a low-speed gear 204 b and a first intermediate gear 204 c, sothat the output shaft 205 can be rotated at an increasing speed furthervia a second intermediate gear 204 e and a high-speed gear 204 f.

As bearings for rotatably supporting the low-speed shaft 204 a, theintermediate shaft 204 d and the output shaft 205 of the speed-up gear202, roller bearings 206 to 211 are frequently used (see, for example,Patent Document 1).

RELATED ART DOCUMENTS Patent Documents

Patent Document 1: JP-A-2007-232186

Patent Document 2: JP-A-H04-344198

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

In the above-described wind power generation device, in the rollerbearing supporting the output shaft rotating at a high speed, smearing(a phenomenon in which a seizure is caused in a surface layer) occurs ona rolling contact surface of a roller or a raceway surface of a turningwheel, which causes a problem in which the lifetime of the rollerbearing is reduced.

In consideration of this problem, the present applicant has found andproposed, as a result of earnest examination on the occurrence mechanismof the smearing, that it is effective, for suppressing the occurrence ofthe smearing, to provide a one-way clutch between an output shaft of aspeed-up gear and a drive shaft of a power generator. This proposal hasbeen filed to Japanese Patent Office as Japanese Patent Application No.2011-198354 and published as JP-A-2013-060825. It is noted that JapanesePatent Application No. 2011-198354 was not published (namely, wasunknown) when applications to which the present application claimspriority (specifically, Japanese Patent Application No. 2013-048593,Japanese Patent Application No. 2013-048618, Japanese Patent ApplicationNo. 2013-048628 and Japanese Patent Application No. 2013-048642) werefiled. Incidentally, a technique of providing a one-way clutch betweenan output shaft of a speed-up gear and a drive shaft of a powergenerator for a different purpose is disclosed in Patent Document 2mentioned above.

One aspect of the present invention is accomplished in consideration ofsuch actual circumstances, and an object is to provide a wind powergeneration device in which the occurrence of smearing in a rollingbearing which supports an output shaft of a speed-up gear can beeffectively suppressed.

Means for Solving the Problem

A first aspect of the present invention provides a wind power generationdevice including: a wind receiving member which receives a wind force torotate a main shaft; a speed-up gear which includes a rotationtransmission mechanism which receives rotation of the main shaft toincrease the rotation in speed, and a rolling bearing which rotatablysupports an output shaft which outputs a running torque of the rotationtransmission mechanism; a power generator which includes an input shaftwhich rotates by receiving rotation of the output shaft and, whichgenerates power in accordance with rotation of a rotor which rotatesintegrally with the input shaft; an input rotating body which isintegrally rotatably provided on the output shaft; an output rotatingbody which is integrally rotatably provided on the input shaft and whichis coaxially disposed radially inside or radially outside the inputrotating body; and a one-way clutch which is disposed between the inputrotating body and the output rotating body, which integrally rotatablyconnects the input rotating body and the output rotating body to eachother in a state in which a rotational speed of the input rotating bodyexceeds a rotational speed of the output rotating body, and which breaksconnection between the input rotating body and the output rotating bodyin a state in which the rotational speed of the input rotating body islower than the rotational speed of the output rotating body, wherein theinput rotating body and the output rotating body are allowed torelatively move along an axial direction, and a maximum allowance ofmovement thereof is set to be larger than variation of a distance alongthe axial direction between the input shaft and the output shaft causedby state change.

A second aspect of the present invention provides a wind powergeneration device including: a speed-up gear which increases a speed ofrotation of a main shaft caused by a wind force to output the rotationincreased in speed from an output shaft; a power generator whichincludes an input shaft which rotates by receiving the rotation of theoutput shaft, and which generates power in accordance with rotation of arotor which rotates integrally with the input shaft; and a one-wayclutch which is provided between the output shaft and the input shaft,which integrally rotatably connects the output shaft and the input shaftto each other in a state in which a rotational speed of the output shaftexceeds a rotational speed of the input shaft, and which breaksconnection between the output shaft and the input shaft in a state inwhich the rotational speed of the output shaft is lower than therotational speed of the input shaft, wherein the one-way clutchincludes: a ring which is fit on a rotating body which rotates with theoutput shaft; another circumferential surface which is disposed tooppose outside or inside of a circumferential surface of the ring in aradial direction and which is provided on a side of the input shaft; anda plurality of engaging elements disposed in a space between thecircumferential surfaces, wherein the output shaft and the input shaftare integrally rotatably connected to each other by causing the engagingelements to engage the circumferential surfaces, and the connection isbroken by releasing the engagement therebetween, wherein a maximumtransmission torque T1max to be transmitted from the rotating body tothe ring when a load torque for operating the power generator is maximumand a transmission torque T2 which can be transmitted from the rotatingbody to the ring with a tightening force obtained by fitting the ring onthe rotating body satisfy a relationship of T1max>T2, and wherein anecessary minimum transmission torque T1 to be transmitted from therotating body to the ring for operating the power generator, atransmission torque T3 which can be transmitted from the rotating bodyto the ring with a tightening force obtained by engagement of theengaging elements with the circumferential surfaces, and thetransmission torque T2 satisfy a relationship of T1<T2+T3.

A third aspect of the present invention provides a wind power generationdevice including: a speed-up gear which increases a speed of rotation ofa main shaft caused by a wind force to output the rotation increased inspeed from an output shaft; a power generator which includes an inputshaft which rotates by receiving the rotation of the output shaft, andwhich generates power in accordance with rotation of a rotor whichrotates integrally with the input shaft; and a one-way clutch which isprovided between the output shaft and the input shaft, which integrallyrotatably connects the output shaft and the input shaft to each other ina state in which a rotational speed of the output shaft exceeds arotational speed of the input shaft, and which breaks connection betweenthe output shaft and the input shaft in a state in which the rotationalspeed of the output shaft is lower than the rotational speed of theinput shaft, wherein the one-way clutch includes: a ring which is fit ona rotating body which rotates with the input shaft; anothercircumferential surface disposed to oppose outside or inside acircumferential surface of the ring in a radial direction and which isprovided on a side of the output shaft; and a plurality of engagingelements disposed in a space between the circumferential surfaces,wherein the output shaft and the input shaft are integrally rotatablyconnected to each other by causing the engaging elements to engage thecircumferential surfaces, and the connection is broken by releasing theengagement therebetween, wherein a maximum transmission torque T1max tobe transmitted from the rotating body to the ring when a load torque foroperating the power generator is maximum and a transmission torque T2which can be transmitted from the rotating body to the ring with atightening force obtained by fitting the ring on the rotating bodysatisfy a relationship of T1max>T2, and wherein a necessary minimumtransmission torque T1 to be transmitted from the rotating body to thering for operating the power generator, a transmission torque T3 whichcan be transmitted from the rotating body to the ring with a tighteningforce obtained by engagement of the engaging elements with thecircumferential surfaces, and the transmission torque T2 satisfy arelationship of T1<T2+T3.

A fourth aspect of the present invention provides a wind powergeneration device including: a main shaft which rotates by a wind force;a speed-up gear which increases a speed of rotation of the main shaftand which outputs the rotation increased in speed from an output shaft;a power generator which includes an input shaft rotated by receiving therotation of the output shaft and which generates power in accordancewith rotation of a rotor which rotates integrally with the input shaft;a casing which houses the speed-up gear and the power generator; aninput rotating body which is integrally rotatably provided on the outputshaft; an output rotating body which is integrally rotatably provided onthe input shaft and which is disposed coaxially radially inside orradially outside the input rotating body; a one-way clutch which isdisposed between the input rotating body and the output rotating body,which integrally rotatably connects the input rotating body and theoutput rotating body to each other in a state in which a rotationalspeed of the input rotating body exceeds a rotational speed of theoutput rotating body, and which breaks connection between the inputrotating body and the output rotating body in a state in which therotational speed of the input rotating body is lower than the rotationalspeed of the output rotating body; and shielding means which shields aregion where the one-way clutch is disposed from a space within thecasing.

A fifth aspect of the present invention provides a power generationdevice including: a main shaft which rotates by an external force; aspeed-up gear which increases a speed of rotation received from the mainshaft and which outputs the rotation increased in speed from an outputshaft; a power generator which includes a drive shaft which rotates byreceiving the rotation of the output shaft and a rotor which rotatesintegrally with the drive shaft, and which generates power in accordancewith the rotation of the rotor; a one-way clutch which is providedbetween the output shaft and the drive shaft, which integrally rotatablyconnects the output shaft and the drive shaft to each other in a firststate in which a rotational speed of the output shaft exceeds arotational speed of the drive shaft, and which breaks connection betweenthe output shaft and the drive shaft in a second state in which therotational speed of the output shaft is lower than the rotational speedof the drive shaft; connecting means which is provided between theoutput shaft and the drive shaft and which is capable of integrallyrotatably connecting the output shaft and the drive shaft to each otherat least in the second state; and a control unit which controls anoperation of the connecting means to connect the output shaft and thedrive shaft to each other in accordance with a prescribed condition.

Advantages of the Invention

According to the aspects of the present invention, the occurrence ofsmearing in the rolling bearing which supports the output shaft of thespeed-up gear can be effectively suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view of a wind power generation deviceaccording to a first embodiment of the present invention.

FIG. 2 is a schematic side view of a speed-up gear and a powergenerator.

FIG. 3 is a side view (a partial cross-sectional view) of a shaftcoupling device.

FIG. 4 is a cross-sectional view taken on arrow A-A of FIG. 3.

FIG. 5 is a cross-sectional view of a shaft coupling device in which aone-way clutch and a rolling bearing are enlargedly illustrated.

FIG. 6 is an enlarged cross-sectional view of a principal part of theone-way clutch.

FIG. 7 is a perspective view of a cage of the one-way clutch.

FIGS. 8(a) and 8(b) are explanatory diagrams illustrating the action ofthe one-way clutch.

FIG. 9 is a graph explaining the relationship between a load torque anda transmission torque.

FIGS. 10(a) to 10(d) are explanatory diagrams illustrating assemblyprocedures of the shaft coupling device.

FIG. 11 is a cross-sectional view of a roller bearing of the speed-upgear.

FIG. 12 is an enlarged cross-sectional view of a connecting portion of acovering member.

FIG. 13 is a cross-sectional view of a shaft coupling device of a windpower generation device according to a second embodiment of the presentinvention.

FIG. 14 is an enlarged cross-sectional view of a principal part of aone-way clutch.

FIG. 15 is a schematic side view of a modification of the wind powergeneration device.

FIG. 16 is a schematic side view of a speed-up gear and a powergenerator according to another embodiment.

FIG. 17 is a cross-sectional view of a shaft coupling device accordingto still another embodiment in which a one-way clutch and a rollingbearing are enlargedly illustrated.

FIG. 18 is a cross-sectional view of a shaft coupling device accordingto still another embodiment in which a one-way clutch and a rollingbearing are enlargedly illustrated.

FIG. 19 is a schematic side view of a wind power generation deviceaccording to a third embodiment of the present invention.

FIG. 20 is a cross-sectional view of a connecting portion between anoutput shaft of a speed-up gear and a drive shaft of a power generatorin the wind power generation device in which structures of a one-wayclutch and a rolling bearing are illustrated particularly in details.

FIG. 21 is a cross-sectional view of the one-way clutch of the windpower generation device.

FIG. 22 is a cross-sectional view of the connecting portion between theoutput shaft of the speed-up gear and the drive shaft of the powergenerator in the wind power generation device in which structures of theone-way clutch, an electromagnetic clutch and the rolling bearing areillustrated particularly in details.

FIG. 23 is a cross-sectional view illustrating a speed-up gear accordingto the background art.

MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will now be describedwith reference to the accompanying drawings.

FIG. 1 is a schematic side view of a wind power generation deviceaccording to a first embodiment of the present invention.

The wind power generation device 1 includes a blade (wind receivingmember) 11, a column 12 and a nacelle 13. The blade 11 includes aplurality of wings provided at the tip of a main shaft 2, and rotatesthe main shaft 2 by receiving wind. The nacelle 13 includes the mainshaft 2, a support mechanism 15 for supporting the main shaft 2, aspeed-up gear 3 for increasing the speed of the rotation of the mainshaft 2, a power generator 4 for generating power by a rotational forceincreased in speed by the speed-up gear 3, a casing 18 for housing thesecomponents, and the like. The column 12 supports the nacelle 13horizontally rotatably around a vertical axis.

FIG. 2 is a schematic side view of the speed-up gear and the powergenerator.

The power generator 4 is formed by, for example, an induction generator,and includes a drive shaft (input shaft) 41 that is rotated by receivingthe rotation, having been increased in speed by the speed-up gear 3, arotor 42 built in the power generator 4, and a stator and the like notshown. The rotor 42 is integrally rotatably connected to the drive shaft41, and the power generator 4 is configured to generate power as aresult of driving the rotor 42 by the rotation of the drive shaft 41.Besides, the drive shaft 41 is provided with a brake 44 for braking thedrive shaft 41.

The speed-up gear 3 includes a gear mechanism (rotation transmissionmechanism) 30 that receives the rotation of the main shaft 2 to increasethe speed of the rotation. The gear mechanism 30 includes a planetarygear mechanism 31, and a high-speed stage gear mechanism 32 thatreceives the rotation having been increased in speed by the planetarygear mechanism 31 to further increase its speed.

The planetary gear mechanism 31 includes an internal gear (ring gear) 31a, a plurality of planetary gears 31 b held on a planetary carrier (notshown) integrally rotatably connected to the main shaft 2, and a sungear 31 c engaged with the planetary gears 31 b. Thus, when theplanetary carrier is rotated together with the main shaft 2, the sungear 31 c is rotated via the planetary gears 31 b, and the rotation istransmitted to a low-speed shaft 33 of the high-speed stage gearmechanism 32.

The high-speed stage gear mechanism 32 includes the low-speed shaft 33having a low-speed gear 33 a, an intermediate shaft 34 having a firstintermediate gear 34 a and a second intermediate gear 34 b, and anoutput shaft 35 having a high-speed gear 35 a.

The low-speed shaft 33 is formed by a large rotating shaft having adiameter of, for example, about 1 m, and is disposed coaxially with themain shaft 2. Both end portions along the axial direction of thelow-speed shaft 33 are rotatably supported by roller bearings 36 a and36 b.

The intermediate shaft 34 is disposed above the low-speed shaft 33, andboth end portions thereof along the axial direction are rotatablysupported by roller bearings 37 a and 37 b. The first intermediate gear34 a of the intermediate shaft 34 is engaged with the low-speed gear 33a, and the second intermediate gear 34 b is engaged with the high-speedgear 35 a.

The output shaft 35 is disposed above the intermediate shaft 34, so asto output a running torque. A first end portion 35 b and a second endportion (an output end portion) 35 c along the axial direction of theoutput shaft 35 are rotatably supported respectively by roller bearings38 and 39.

Owing to the above-described structure, the speed of the rotation of themain shaft 2 is increased in three stages by a gear ratio of theplanetary gear mechanism 31, a gear ratio between the low-speed gear 33a and the first intermediate gear 34 a, and a gear ratio between thesecond intermediate gear 34 b and the high-speed gear 35 a, so that therunning torque can be output from the output end portion 35 c of theoutput shaft 35. In other words, the rotation of the main shaft 2 causedby wind is increased in speed in three stages by the speed-up gear 3 todrive the power generator 4.

FIG. 11 is a cross-sectional view of the roller bearing of the speed-upgear supporting, for example, the first end portion 35 b of the outputshaft 35. In FIG. 11, the roller bearing 38 is formed by a cylindricalroller bearing, and includes an inner ring 38 a externally fit and fixedon the output shaft 35, an outer ring 38 b fixed on a housing (notshown), a plurality of cylindrical rollers 38 c disposed to be movableby rolling between the inner ring 38 a and the outer ring 38 b, and aring-shaped cage 38 d for holding the cylindrical rollers 38 c atprescribed intervals along the circumferential direction. The inner ring38 a, the outer ring 38 b and the cylindrical rollers 38 c are made of,for example, bearing steel, and the cage 38 d is made of, for example, acopper alloy.

The inner ring 38 a has an inner ring raceway surface 38 a 1 formed in acenter portion along the axial direction on the outer circumferencethereof. The outer ring 38 b is disposed coaxially with the inner ring38 a, and includes an outer ring raceway surface 38 b 1 formed in acenter portion along the axial direction on the inner circumferencethereof, and a pair of outer ring flange portions 38 b 2 formed on bothsides along the axial direction of the outer ring raceway surface 38 b1. The outer ring raceway surface 38 b 1 is disposed to oppose the innerring raceway surface 38 a 1. The outer ring flange portions 38 b 2 areformed to protrude, radially inward, from both end portions along theaxial direction of the inner circumference of the outer ring 38 b, andthe end surfaces of the cylindrical rollers 38 c are in sliding contactwith these outer ring flange portions 38 b 2.

The cylindrical rollers 38 c are disposed to be movable by rollingbetween the inner ring raceway surface 38 a 1 of the inner ring 38 a andthe outer ring raceway surface 38 b 1 of the outer ring 38 b.

The cage 38 d includes a pair of ring portions 38 d 1 disposed to bespaced from each other along the axial direction, and a plurality ofpillar portions 38 d 2 disposed at equal intervals along thecircumferential direction of the ring portions 38 d 1 to connect thering portions 38 d 1 to each other. Pockets 38 d 3 are formed betweenthe pair of ring portions 38 d 1 and the pillar portions 38 d 2 adjacentto each other, and each cylindrical roller 38 c is disposed in eachpocket 38 d 3. Incidentally, in the wind power generation device 1having a large size, a large load is applied to the roller bearingsupporting the output shaft 35 of the speed-up gear 3, and therefore,the used roller bearing 38 preferably has high rigidity and can suitablyabsorb thermal expansion/contraction along the axial direction of theoutput shaft 35. It is noted that a ball bearing or a conical bearingcan be used as the rolling bearing.

In FIG. 2, the wind power generation device 1 includes a shaft couplingdevice (coupling device) 9 for integrally rotatably connecting theoutput shaft 35 of the speed-up gear 3 and the drive shaft 41 of thepower generator 4 to each other. This shaft coupling device 9 includesan input rotating body (inside rotating body) 5, an output rotating body(outside rotating body) 6, a one-way clutch 7, and rolling bearings 8,and is formed also as a clutch unit. Besides, the shaft coupling device9 is provided on a side of the brake 44 for the drive shaft 41 closer tothe speed-up gear 3.

FIG. 3 is a side view (partial cross-sectional view) of the shaftcoupling device. FIG. 4 is a cross-sectional view taken on arrow A-A ofFIG. 3.

The input rotating body 5 includes a shaft portion 51 and an input-sideconnecting portion 52 provided in a first end portion (a left endportion in FIG. 3) along the axial direction of the shaft portion 51.The input-side connecting portion 52 is integrally rotatably andremovably connected to the output shaft 35.

The output rotating body 6 is disposed coaxially with the input rotatingbody 5 and includes a cylindrical portion 61 formed in a cylindricalshape, and an output-side connecting portion 62 provided in a second endportion (a right end portion in FIG. 3) along the axial direction of thecylindrical portion 61. The output-side connecting portion 62 isintegrally rotatably and removably connected to the drive shaft 41.

The one-way clutch 7 is disposed in a portion between the input rotatingbody 5 and the output rotating body 6 where the rotors radially opposeand overlap each other. Besides, the rolling bearings 8 are disposedbetween the input rotating body 5 and the output rotating body 6 and onboth sides along the axial direction of the one-way clutch 7. Theone-way clutch 7 is provided for transmitting the rotation of the outputshaft 35 via the input rotating body 5 and the output rotating body 6 tothe drive shaft 41 in a connectable/disconnectable manner, and therolling bearings 8 are provided for mutually supporting the output shaft35 and the drive shaft 41. Incidentally, although the rolling bearings 8are disposed on both sides along the axial direction of the one-wayclutch 7 in the wind power generation device 1 of the presentembodiment, a rolling bearing may be disposed on merely one side alongthe axial direction of the one-way clutch 7.

In FIG. 3, the input-side connecting portion 52 includes a flangeportion 52 a fixed on one end of the shaft portion 51, and a bendingmember 52 b disposed between the flange portion 52 a and the outputshaft 35. The shaft portion 51 is formed in a cylindrical shape, and hasa keyway 51 b formed on an outer circumferential surface in the firstend portion (the left end portion in FIG. 3) thereof along the axialdirection. The flange portion 52 a has, at intervals along thecircumferential direction, a plurality of (four, for example)projections 52 a 1 (see FIG. 4) each in a circular shape and projectingoutward in the radial direction. Each projection 52 a 1 has a boltinsertion hole 52 a 2 formed therethrough. A fitting hole 52 a 3 isformed in the center portion of the flange portion 52 a, and the firstend portion of the shaft portion 51 is fit in this fitting hole 52 a 3by press-fitting or the like. Besides, a keyway 52 a 4 is formed in thefitting hole 52 a 3. The shaft portion 51 and the flange portion 52 aare integrally rotatably connected to each other by providing keys 53 inthe two keyways 52 a 4 and 51 b.

The output-side connecting portion 62 includes a flange portion 62 aprovided in a second end portion along the axial direction of thecylindrical portion 61, and a bending member 62 b disposed between theflange portion 62 a and the drive shaft 41. The flange portion 62 a isintegrally molded in a first end portion of the cylindrical portion 61by forging or the like, protrudes outward in the radial direction fromthe outer circumferential surface of the cylindrical portion 61, and hasa bolt insertion hole 62 a 1 formed therethrough. Besides, the flangeportion 62 a is provided in plural number (of, for example, four) atintervals along the circumferential direction in the same manner as theprojections 52 a 1 of the flange portion 52 a of the input-sideconnecting portion 52.

The bending member 52 b of the input-side connecting portion 52 isdisposed between the flange portion 52 a and a flange portion 35 c 1provided in the output end portion 35 c of the output shaft 35. Besides,the bending member 62 b of the output-side connecting portion 62 isdisposed between the flange portion 62 a and a flange portion 41 aprovided in the input end portion of the drive shaft 41. Each of thesebending members 52 b and 62 b is formed by a plurality of ring-shaped ordisc-shaped members, so as to be connected to the flange portions 52 aand 35 c 1 or 62 a and 41 a with a fastener 52 c or 62 c of a bolt and anut.

Each of these bending members 52 b and 62 b has a function to absorb amisalignment, such as eccentricity or angle deviation (deviation of theaxial center), between the output shaft 35 and the drive shaft 41 by itsown bend (elastic deformation). The structures of these bending members52 b and 62 b and the structures of the flange portions 52 a, 35 c 1, 62a and 41 a used in combination are not especially limited, and any ofknown structures (such as structures described in, for example,JP-A-2006-250034 and JP-A-2001-349335) may be employed as long as it hasthe above-described function. Besides, the input-side connecting portion52 may include, as its component, the flange portion 35 c 1 on the sideof the output shaft 35, and the output-side connecting portion 62 mayinclude, as its component, the flange portion 41 a on the side of thedrive shaft 41.

Between the shaft portion 51 of the input rotating body 5 and thecylindrical portion 61 of the output rotating body 6, a grease(lubricant) is filled for lubricating the one-way clutch 7 and therolling bearings 8 disposed therein. The shaft coupling device 9includes sealing means 10 for forming a closed space for filling thegrease between the shaft portion 51 and the cylindrical portion 61 wherethe one-way clutch 7 and the rolling bearings 8 are housed. The sealingmeans 10 includes a ring-shaped seal receiving member 101 fit around theouter circumferential surface of the shaft portion 51 between the leftrolling bearing 8 and the flange portion 52 a of the input rotating body5, a ring-shaped first sealing member 102 provided in a gap between theouter circumferential surface of the seal receiving member 101 and theinner circumferential surface of the cylindrical portion 61 of theoutput rotating body 6, a covering member 103 for covering an opening ona right side of the cylindrical portion 61, and a second sealing member104 including an O-ring provided between the covering member 103 and theend surface of the cylindrical portion 61. The covering member 103 ismade of a metal plate formed in a circular shape, and is removablyattached to a base of the flange portion 62 a with a fitting screw 103a. Such sealing means 10 is provided so that the grease can be sealedbetween the shaft portion 51 of the input rotating body 5 and thecylindrical portion 61 of the output rotating body 6 and that theone-way clutch 7 and the rolling bearings 8 can be suitably lubricated.

Incidentally, the region of the one-way clutch 7 and the regions of therolling bearings 8 in the closed space between the shaft portion 51 andthe cylindrical portion 61 are communicated with each other in the axialdirection, so that the grease can be spread between the one-way clutch 7and the rolling bearings 8. Besides, since the grease is liable to becollected on the radially outside due to the centrifugal force, theseregions of the closed space preferably communicate on the side of anouter ring inner circumferential surface 72 a of the one-way clutch 7and an outer ring raceway surface 82 a of the rolling bearing 8 as inthe present embodiment.

Besides, on the outer circumference of the cylindrical portion 61, anoil supply hole 61 a equipped with a grease nipple (an oil supply portequipped with a check valve) 64 is formed to penetrate along the radialdirection into the closed space. This oil supply hole 61 a is providedcorrespondingly to a position between the one-way clutch 7 and one ofthe rolling bearings 8. Specifically, the oil supply hole 61 a is formedcorrespondingly to a position between the outer ring innercircumferential surface 72 a of the one-way clutch 7 and the outer ringraceway surface 82 a of the rolling bearing 8. Besides, the oil supplyhole 61 a is provided in a plurality of positions along thecircumferential direction, for example, in four positions at equalintervals as illustrated in FIG. 4, so that the grease can be suppliedinto the closed space through any of the oil supply holes 61 a.

Furthermore, in supplying the grease through any of the oil supply holes61 a, waste grease can be discharged through another oil supply hole 61a by removing the grease nipple 64 from this oil supply hole 61 a.Accordingly, the oil supply holes 61 a have not only the function as agrease supply part but also the function as a discharge part. It isnoted that the grease can be discharged not only through the oil supplyhole 61 a but also by removing the covering member 103 from the outputrotating body 6. In this case, since the opening at the end of thecylindrical portion 61 can be wholly opened, the grease can beefficiently discharged.

When the output rotating body 6 rotates, the positions of the oil supplyholes 61 a are changed, but since the oil supply holes 61 a are providedin the plural positions along the circumferential direction, the oilsupply hole 61 a disposed in a position where the grease can be mosteasily supplied can be selectively used for the grease supply.Accordingly, an oil supply operation can be easily performed.

Besides, since the oil supply hole 61 a is provided correspondingly tothe position between the one-way clutch 7 and one of the rollingbearings 8, the grease can be definitely supplied to both of them. Theoil supply hole 61 a can be provided correspondingly to a positionbetween the one-way clutch 7 and the other of the rolling bearings 8, orpositions between the one-way clutch 7 and both of the rolling bearings8. Incidentally, the grease used for lubricating the one-way clutch 7 ispreferably a grease containing an ester as a base oil and a urea-basedthickener so that it is difficult to be affected by temperature change,which does not limit the present invention.

Between the end surface of the first end portion (the left end portionin FIG. 3) along the axial direction of the cylindrical portion 61 andthe end surface of the flange portion 52 a of the input rotating body 5opposing the former end surface, a space s2 is formed. Besides, betweenthe tip of the shaft portion 51 and the covering member 103, a space s3is formed. Owing to these spaces s2 and s3, the output rotating body 6is movable along the axial direction against the input rotator 5 withthe output rotating body 6 disconnected from the drive shaft 41.

FIG. 5 is a cross-sectional view of the shaft coupling device in whichthe one-way clutch and the rolling bearings are enlargedly illustrated.

As illustrated in FIGS. 4 and 5, the one-way clutch 7 includes an innerring 71, an outer ring 72 and a plurality of rollers (engaging elements)73 disposed between an outer circumferential surface 71 a of the innerring 71 and the inner circumferential surface 72 a of the outer ring 72.

The inner ring 71 is fixed by fitting around a center portion along theaxial direction of the shaft portion 51 of the input rotating body 5, soas to be rotated integrally with the shaft portion 51. A region B of acenter portion along the axial direction of the cylindrical portion 61of the outer rotor 6 corresponds to the outer ring 72 of the one-wayclutch 7. Accordingly, the inner circumferential surface in the region Bof the cylindrical portion 61 corresponds to the outer ring innercircumferential surface 72 a where the rollers 73 move by rolling. Inthe present embodiment, the rollers 73 are formed each in a cylindricalshape and are provided in number of eight arranged along thecircumferential direction.

The one-way clutch 7 further includes a ring-shaped cage 74 for holdingthe respective rollers 73 at prescribed intervals along thecircumferential direction, and a plurality of elastic members (pressingmembers) 75 elastically pressing the rollers 73 in one direction.

FIG. 7 is a perspective view of the cage of the one-way clutch. In FIG.7, the cage 74 includes a pair of ring portions 76 opposing each otheralong the axial direction, and a plurality of pillar portions 77 formedseparately from the ring portions 76 and having end portions along theaxial directions respectively fit in the ring portions 76. Spacessurrounded by the ring portions 76 and the pillar portions 77 adjacentto each other along the circumferential direction form pockets 78, andeach of the rollers 73 is individually held in each pocket 78 (see FIG.4).

Each of the ring portions 76 is made of a metal material such as carbonsteel or aluminum, and is set to have, for example, an outer diameter of300 mm and a thickness along the axial direction of 15 mm. On the innercircumference of each ring portion 76, a plurality of recesses 76 a areformed at prescribed intervals along the circumferential direction.

Each of the pillar portions 77 includes a main body 77 a, a projection77 b protruding on one end surface along the circumferential directionof the main body 77 a, and a pair of fitting portions 77 c formed inboth end portions along the axial direction of the main body 77 a. Themain body 77 a, the projection 77 b and the fitting portions 77 c areintegrally molded by injection molding a synthetic resin material.

The projection 77 b guides (aligns) the elastic member 75 held in thepocket 78 as illustrated in FIG. 4. Specifically, the projection 77 b isformed to be gradually tapered toward the tip thereof. The elasticmember 75 is freely fit from the tip side of the projection 77 b. It isnoted that the elastic member 75 is made of a compression coil springformed to be elongated along the axial direction. The elastic member 75may be, however, another type of spring such as a plate spring.

As illustrated in FIG. 7, the fitting portion 77 c is formed to have asmaller thickness along the radial direction than the main body 77 a,and the thickness of the fitting portion 77 c is set so that the outercircumferential surface of the ring portion 76 and the outercircumferential surface of the main body 77 a can be substantially atthe same level when the fitting portion 77 c is fit in the recess 76 a.

In this manner, the cage 74 includes the ring portions 76 and the pillarportions 77, and these are formed as separate components, and hence, thering portions 76 and the pillar portions 77 can be individuallyproduced. Accordingly, as compared with a case where the whole cage 74is integrally produced, the cage 74 can be easily produced. Inparticular, the cage 74 used in the wind power generation device 1 has alarge size, and it is difficult to integrally produce it, and hence, itis more beneficial to construct the ring portions 76 and the pillarportions 77 as separate components. Besides, since the ring portions 76are made of a metal, the strength of the cage 74 can be sufficientlysecured, and since the pillar portions 77 are made of a synthetic resin,the weight of the whole cage 74 can be reduced.

As illustrated in FIG. 4, flat cam surfaces 71 a 1 in the same number(namely, eight) as the rollers 73 are formed on the outercircumferential surface 71 a of the inner ring 71, and the innercircumferential surface 72 a of the outer ring 72 is formed as acylindrical surface. A plurality of (eight) wedge-shaped spaces S areformed along the circumferential direction between the cam surfaces 71 a1 of the inner ring 71 and the cylindrical surface 72 a of the outerring 72.

FIG. 6 is an enlarged cross-sectional view of a principal part of theone-way clutch.

Each roller 73 is individually disposed in each wedge-shaped space S.Besides, the roller 73 is pressed by the elastic member 75 toward adirection where the wedge-shaped space S becomes smaller. The roller 73has, as its outer circumferential surface, a contact surface 73 a incontact with the cam surface 71 a 1 of the inner ring 71 and the innercircumferential surface 72 a of the outer ring 72, and this contactsurface 73 a is formed to extend straight along the width direction (theaxial direction).

In the one-way clutch 7 having the aforementioned structure, if theinput rotating body 5 rotates at an increasing speed and as a result,the rotational speed of the input rotating body 5 exceeds the rotationalspeed of the output rotating body 6, the inner ring 71 is to rotaterelatively against the outer ring 72 in one direction (thecounterclockwise direction in FIG. 4; a direction of an arrow a in FIG.6). In this case, the roller 73 slightly moves, owing to the pressingforce applied by the elastic member 75, in the direction where thewedge-shaped space S becomes smaller (in the rightward direction in FIG.6), the contact surface 73 a of the roller 73 is pressed against theouter circumferential surface 71 a (the cam surface 71 a 1; an engagedsurface) of the inner ring 71 and the inner circumferential surface (anengaged surface) 72 a of the outer ring 72, and hence, the roller 73 isengaged with the inner and outer rings 71 and 72. As a result, the innerand outer rings 71 and 72 can integrally rotate in the direction a, andhence, the input rotating body 5 and the output rotating body 6 can beintegrally rotatably connected to each other.

Besides, if the input rotating body 5 rotates at a constant speed afterrotating at an increasing speed and as a result, the rotational speed ofthe input rotating body 5 becomes the same as the rotational speed ofthe output rotating body 6, the roller 73 is held in a state where it isengaged with the inner and outer rings 71 and 72. Therefore, the one-wayclutch 7 retains the integral rotation along the above-described onedirection of the inner and outer rings 71 and 72, and hence, the inputrotating body 5 and the output rotating body 6 continues to integrallyrotate.

On the other hand, if the input rotating body 5 rotates at a decreasingspeed and as a result, the rotational speed of the input rotating body 5becomes lower than the rotational speed of the output rotating body 6,the inner ring 71 is to rotate relatively against the outer ring 72 inanother direction (the clockwise direction of FIG. 4; a direction of anarrow b in FIG. 6). In this case, the roller 73 slightly moves, againstthe pressing force applied by the elastic member 75, in a directionwhere the wedge-shaped space S becomes larger, and thus, the engagementbetween the roller 73 and the inner and outer rings 71 and 72 isreleased. Since the engagement of the roller 73 is thus released, theconnection between the input rotating body 5 and the output rotatingbody 6 is broken.

Incidentally, the outer ring inner circumferential surface 72 a formingthe respective wedge-shaped spaces S is formed by parts (arc surfaces)of the cylindrical surface continuous along the circumferentialdirection, but it may be formed by arc surfaces not continuous along thecircumferential direction, such as independent arc surfaces having aflat surface or an infection point between portions of the outer ringinner circumferential surface 72 a corresponding to the wedge-shapedspaces S adjacent to each other.

In the input rotating body 5, the inner ring 71 of the one-way clutch 7is fit on the shaft portion 51 by interference fit with a prescribedinterference. Accordingly, the shaft portion 51 and the inner ring 71can integrally rotate owing to a tightening force of the inner ring 71on the shaft portion 51. Besides, the tightening force of the inner ring71 on the shaft portion 51 is increased by the engagement between theroller 73 and the inner and outer rings 71 and 72. This action will nowbe described in details.

As illustrated in FIG. 6, when the inner ring 71 is to rotate relativelyagainst the outer ring 72 in the direction of the arrow a in FIG. 6, theroller 73 is engaged with the cam surface 71 a 1 and the outer ringinner circumferential surface 72 a, and as a result, as illustrated inFIGS. 8(a) and 8(b), a load Fa or Fb is applied by the outer ring innercircumferential surface 72 a to the roller 73, and a vertical componentload Fa1 or Fb1, that is, a force component of the load Fa or Fb, isapplied by the roller 73 to the cam surface 71 a 1 of the inner ring 71.Accordingly, the tightening force of the inner ring 71 on the shaftportion 51 is increased by this vertical component load Fa1 or Fb1.

As a result, a torque (transmission torque) T2 that can be transmittedfrom the shaft portion 51 to the inner ring 71 owing to the tighteningforce caused by the fit between the shaft portion 51 and the inner ring71 (hereinafter also referred to as the “initial tightening force”) canbe set to be smaller than a maximum transmission torque T1max to betransmitted from the shaft portion 51 to the inner ring 71 when a loadtorque for operating the wind power generation device 1 (such as apower-generation torque for driving the rotor 42 of the power generator4 and an inertia torque) is the maximum. In other words, the followingrelationship can be set between T2 and T1max:T1max>T2  (1)

Besides, assuming that a transmission torque that can be transmittedfrom the shaft portion 51 to the inner ring 71 owing to a tighteningforce caused by the engagement between the roller 73 and the inner andouter rings 71 and 72 (hereinafter also referred to as the “additionaltightening force”) is T3, a sum of T2 and T3 is always larger than aminimum transmission torque T1 necessary for operating the wind powergeneration device 1. In other words, the following relationship holds:T1<T2+T3  (2)

In particular, a transmission torque T3max that can be transmitted fromthe shaft portion 51 to the inner ring 71 owing to the additionaltightening force when the load torque is the maximum satisfies thefollowing condition:T1max<T2+T3max  (3)

The relationships among the load torque and the respective transmissiontorques T1 to T3 are illustrated in a graph of FIG. 9. Incidentally, theabove-described maximum load torque refers to a maximum load torqueassumed as a design condition of the wind power generation device 1, andis not an excessive load torque occurring when the wind power generationdevice 1 has a malfunction or when the wind speed is unexpectedlyabruptly varied due to abnormal weather.

When the aforementioned relationships (1) to (3) are satisfied, theinitial tightening force caused by the fit between the shaft portion 51and the inner ring 71 can be made as small as possible, and hence theinterference necessary for the fit therebetween can be reduced, so thatan internal stress (in particular, a stress along the circumferentialdirection) caused in the inner ring 71 due to the fit therebetween canbe reduced. Since the internal stress of the inner ring 71 is reduced,the durability of the inner ring 71 can be increased, so that thelifetime of the one-way clutch 7, and the lifetime of the shaft couplingdevice 9 in the end can be increased. It is noted that the interferencebetween the shaft portion 51 and the inner ring 71 can be set to 10 μmat a minimum.

Incidentally, if the inner ring 71 of the one-way clutch 7 is omittedand the cam surface is directly formed on the shaft portion 51,concentration of the stress described above caused due to the fit can besuitably suppressed. Since the one-way clutch 7 used in the wind powergeneration device 1 as in the present embodiment has a large size,however, it is difficult and is not realistic to form the cam surfacedirectly on the shaft portion 51. Accordingly, it is the most effectiveto set the relationships among the transmission torque T1 to T3 and theload torque as the aforementioned conditions (1) to (3).

On the other hand, if the tightening force obtained through theengagement between the roller 73 and the inner and outer rings 71 and 72becomes excessively large when the load torque is increased, the burdenof the inner ring 71 is increased, and hence, it is apprehended that thedurability may be lowered on the contrary. Therefore, in the presentembodiment, as the load torque is increased, the increment of thevertical component load applied by the roller 73 to the inner ring 71(the cam surface 71 a 1) corresponding to the increment of the loadtorque is reduced, so that the burden of the inner ring 71 can bereduced as much as possible.

Specifically, as illustrated in FIG. 6, the outer ring innercircumferential surface 72 a is formed as an arc surface, and therefore,as the wedge-shaped space S is smaller, the wedge angle is larger. FIG.8(a) illustrates a state where the roller 73 is positioned in a regionwhere the wedge-shaped space S is comparatively large and a wedge angleθa is small, and FIG. 8(b) illustrates a state where the roller 73 ispositioned in a region where the wedge-shaped space S is comparativelysmall and a wedge angle θb is large.

Besides, the roller 73 is positioned in the region where thewedge-shaped space S is comparatively large in a case where the loadtorque is small, such as an initial stage of the engagement between theroller 73 and the inner and outer rings 71 and 72, for example, when acut-in wind speed (a minimum wind speed necessary for power generation)is attained from a non-rotating state for starting the rotation, or whenthe rotation becomes constant and stable at the cut-in wind speed.Alternatively, the roller 73 is positioned in the region where thewedge-shaped space S is small in a case where the load torque is large,such as when a wind speed beyond a rated wind speed is attained toobtain a rated output. The cut-in wind speed may be an instantaneouswind speed or an average wind speed of a prescribed time.

Accordingly, in FIGS. 8(a) and 8(b), the loads Fa and Fb applied fromthe outer ring inner circumferential surface 72 a to the roller 73 arein the following relationship:Fa<Fb  (4)

A ratio of the vertical component load Fb1 to the load Fb applied fromthe outer ring inner circumferential surface 72 a to the roller 73(Fb/Fb1) illustrated in FIG. 8(b) is smaller than a ratio of thevertical component load Fa1 to the load Fa (Fa/Fa1) illustrated in FIG.8(a). Therefore, even when the load torque is increased, the verticalcomponent load Fb1 is not much increased, and hence the burden of theinner ring 71 can be reduced.

The wedge angle θa obtained when the load torque at the initial stage ofthe engagement between the roller 73 and the inner and outer rings 71and 72 is applied and the wedge angle θb obtained when the maximum loadtorque is applied are set to be in the following relationship:1.0°<θb−θa<1.5°  (5)

The wedge angle θa is preferably in a range of 4° to 9°, and the wedgeangle θb is preferably in a range of 5.5° to 10°. If the wedge angle θais smaller than 4°, there is a possibility that the vertical componentload Fa1 applied from the roller 73 to the cam surface 71 a 1 may becomelarger than necessary, and if the wedge angle θa exceeds 9°, the otherwedge angle θb becomes too large, and hence there is a possibility thatthe engagement between the roller and the circumferential surfaces maybecome insufficient. Besides, if the wedge angle θb is smaller than5.5°, the other wedge angle θa becomes too small, and hence there is apossibility that the vertical component load Fa1 applied from the roller73 to the cam surface 71 a 1 may become larger than necessary, and ifthe wedge angle θb exceeds 10°, there is a possibility that theengagement between the roller 73 and the inner and outer rings 71 and 72may become insufficient.

In addition, a ratio between the wedge angles θa and θb is set as:1.1<θb/θa<1.4  (6)

(more preferably, 1.11<θb/θa<1.38)

If the wedge angles θa and θb are set to be in the above-describedrelationship, the torque transmission between the shaft portion 51 andthe inner ring 71 can be definitely performed, and in addition, theburden of the inner ring 71 can be reduced from the initial stage of theengagement between the roller 73 and the inner ring 71 and the outerring 72 until the load torque becomes the maximum.

The above-described relationships (5) and (6) can be set by adjustingthe inner diameter of the outer ring 72, the outer diameter and the P.C. D. of the roller 73, the distance between the outer ring innercircumferential surface 72 a and the cam surface 71 a 1, and the like.Besides, the number of the rollers 73 used in the one-way clutch 7 isset preferably to four to eight. If the number of the rollers 73 exceedseight, the loads Fa and Fb applied from the outer ring innercircumferential surface 72 a to each roller 73 are dispersed to reducethe vertical component loads Fa1 and Fb1 applied from the roller 73 tothe cam surface 71 a 1, and there is a possibility that the tighteningforce of the inner ring 71 on the shaft portion 51 cannot besufficiently obtained. Alternatively, if the number of the rollers 73 issmaller than four, the tightening force of the inner ring 71 on theshaft portion 51 becomes too large, and hence a local burden of theinner ring 71 becomes large.

In FIG. 5, the pair of rolling bearings 8 are disposed between the shaftportion 51 of the input rotating body 5 and the cylindrical portion 61of the output rotating body 6, so as to relatively rotatably support theinput rotating body 5 and the output rotating body 6. Besides, therespective rolling bearings 8 are disposed on both sides along the axialdirection of the one-way clutch 7 to be adjacent with washers(positioning members) 91 sandwiched therebetween.

Each rolling bearing 8 is formed by a cylindrical roller bearingincluding an inner ring 81 and an outer ring 82 working as bearingrings, a plurality of cylindrical rollers (rolling elements) 83 disposedbetween the inner ring 81 and the outer ring 82 movably by rolling, anda cage 84 for holding a distance between the plural cylindrical rollers83 along the circumferential direction.

The inner ring 81 has an inner ring raceway surface 81 a formed on itsouter circumference, and inner ring flange portions 81 b formed on bothsides along the axial direction of the inner ring raceway surface 81 ato protrude outward in the radial direction. The end surfaces of thecylindrical roller 83 are in sliding contact with the inside surfaces ofthe inner ring flange portions 81 b. Besides, the inner ring flangeportion 81 b adjacent to the one-way clutch 7 has a radial outer endportion protruding radially outward beyond the inner ring 71 of theone-way clutch 7 so as to be positioned on a side along the axialdirection of the cage 74 of the one-way clutch 7.

Regions A and C of both end portions along the axial direction of thecylindrical portion 61 of the output rotating body 6 correspond to theouter rings 82 of the rolling bearings 8, and the outer ring racewaysurfaces 82 a of the outer rings 82 are formed on the innercircumferential surfaces in these regions A and C. The cylindricalroller 83 is provided movably by rolling between the outer ring racewaysurface 82 a and the inner ring raceway surface 81 a. Accordingly, thecylindrical portion 61 of the outer rotor 6 works also as the outer ring72 of the one-way clutch 7 and the outer rings 82 of the rollingbearings 8, and the outer ring inner circumferential surface 72 a of theone-way clutch 7 and the outer ring raceway surfaces 82 a of the rollingbearings 8 are formed on the same inner circumference. In other words,the outer ring 72 of the one-way clutch 7 and the outer rings 82 of therolling bearings 8 are integrally formed.

Each washer 91 is configured by forming a thin plate material of a metalsuch as an SPCC into a ring shape, and the thickness along the axialdirection of its cross section is set to be smaller than the width alongthe radial direction. Besides, the washer 91 is fit (freely fit) on theouter circumferential surface of the shaft portion 51 of the inputrotating body 5, so as to be sandwiched between the inner ring 71 of theone-way clutch 7 and the inner ring 81 of the rolling bearing 8.Furthermore, the washer 91 protrudes outward in the radial directionbeyond the inner ring 71 of the one-way clutch 7, and can come intocontact with the side surface along the axial direction of the cage 74of the one-way clutch 7.

Accordingly, the cage 74 of the one-way clutch 7 is positioned along theaxial direction by the washer 91. Besides, since the washer 91 isdisposed between the cage 74 of the one-way clutch 7 and the cage 84 ofthe rolling bearing 8, these cages do not directly come into contactwith each other. Therefore, abrasion and seizure caused through thecontact between the cages 74 and 84 can be prevented. Furthermore, sincethe washer 91 is sandwiched between the inner ring 71 of the one-wayclutch 7 and the inner ring 81 of the rolling bearing 8, the washer 91can be firmly fixed even if the washer 91 is freely fit on the shaftportion 51. Accordingly, the washer 91 can be formed to be as thin aspossible, and the cage 74 can be definitely positioned. Besides, theflange portion 81 b formed on the inner ring 81 of the rolling bearing 8protrudes radially outward beyond the inner ring 71 of the one-wayclutch 7 to be positioned on the side along the axial direction of thecage 74, and therefore, the washer 91 can be backed up by the flangeportion 81 b of the inner ring 81, and the washer 91 can be more firmlysupported. As a result, the washer 91 can be formed in a further smallerthickness, and the dimensional increase in the axial direction of theone-way clutch 7 otherwise caused by providing the washer 91 can besuppressed.

Incidentally, the washer 91 is disposed with a gap serving as a passageof the grease provided between the washer and the cylindrical portion 61so as not to inhibit the flow of the grease between the one-way clutch 7and the rolling bearing 8.

FIGS. 10(a) to 10(d) are explanatory diagrams illustrating assemblyprocedures of the shaft coupling device.

Now, the assembly procedures of the shaft coupling device 9 will bedescribed with reference to FIGS. 10(a) to 10(d). First, as illustratedin FIG. 10(a), one of the rolling bearings 8, the washer 91, the innerring 71 of the one-way clutch 7, the ring portion 76, the pillarportions 77 and the other ring portion 76 of the cage 74, the otherrolling bearing 8 are successively attached to the outer circumferentialsurface of the shaft portion 51 of the input rotating body 5. At thispoint, the cage 84 and the cylindrical rollers 83 are mounted to theinner ring 81 of each rolling bearing 8 in advance. The inner ring 81 ofthe rolling bearing 8 and the inner ring 71 of the one-way clutch 7 areattached by fitting on the outer circumferential surface 51 a of theshaft portion 51 by shrink fitting or expansion fitting. Accordingly,the inner rings 81 and 71 are firmly fit on the shaft portion 51 by theinterference fit with a prescribed interference. The cage 74 is attachedby freely fitting one of the ring portions 76 on the outercircumferential surface of the inner ring 71 first, fitting one of thefitting portions 77 c (see FIG. 7) of the pillar portion 77 in eachrecess 76 a (see FIG. 7) of this ring portion 76, and then fitting therecess 76 a of the other ring portion 76 in the other fitting portion 77c of the pillar portion 77 while freely fitting this ring portion 76 onthe inner ring 71.

Next, as illustrated in FIG. 10(b), the seal receiving member 101 is fiton the outer circumferential surface of the shaft portion 51 by theshrink fitting or the like. Besides, the elastic members 75 and therollers 73 of the one-way clutch 7 are attached to the cage 74.

Then, as illustrated in FIG. 10(c), the cylindrical portion 61 of theoutput rotating body 6 is attached to the radial outside of thecylindrical rollers 83 of the rolling bearings 8 and the rollers 73 ofthe one-way clutch 7 having been attached to the input rotating body 5.At this point, as illustrated in FIG. 6, each roller 73 of the one-wayclutch 7 is pressed by the elastic member 75 within the pocket 78 and ispositioned on a side of the end of the cam surface 71 a 1, andtherefore, the roller 73 is in a state where it protrudes radiallyoutward beyond the inner circumferential surface of the cylindricalportion 61 of the output rotating body 6, namely, the outer ring innercircumferential surface 72 a of the one-way clutch 7. Accordingly, whenthe cylindrical portion 61 is to be fit to the radial outside of therollers 73, the cylindrical portion 61 is rotated in an oppositedirection to the direction of pressing the rollers 73 by the elasticmember 75 with the tip (the lower tip in the drawing) of the cylindricalportion 61 kept in contact with the ends of the rollers 73.

In this manner, the rollers 73 can be moved backward to the radialinside while moving toward the center of the cam surface 71 a 1, andhence, the inner circumferential surface of the cylindrical portion 61can be easily fit to the radial outside of the rollers 73.

Besides, since the wind power generation device 1 has a large size andthe respective components of the shaft coupling device 9 are also large,the assembly is performed in an unstable state where these componentsare craned. Therefore, in attaching the cylindrical portion 61 of theoutput rotating body 6 to the radial outside of the rollers 73 of theone-way clutch 7 having been attached to the input rotating body 5, itis difficult to adjust the positions of the tip of the cylindricalportion 61 and the ends of the rollers 73 of the one-way clutch 7.Besides, since the roller 73 is pressed by the elastic member 75 to bepositioned on the side of the radial end of the cam surface 71 a 1, itis necessary to move the roller 73 toward the radial center of the camsurface 71 a 1 for attaching the cylindrical portion 61 to the radialoutside of the roller 73, but the assembly operation is extremelydifficult to perform if the positions of the end of the cylindricalportion 61 and the ends of the rollers 73 of the one-way clutch 7 aredifficult to adjust. In the present embodiment, a tapered surface 61 bfor increasing the inner diameter is formed on the inner circumferentialsurface at the tip of the cylindrical portion 61. When this taperedsurface 61 b is pressed against the end of the roller 73, the positionsof the tip of the cylindrical portion 61 and the end of the roller 73can be easily adjusted, and the tip of the cylindrical portion 61 can beeasily engaged with the end of the roller 73. Furthermore, since thecylindrical portion 61 can be easily held in a state where the taperedsurface 61 b is pressed against the end of the roller 73, the roller 73can be easily moved toward the radial center of the cam surface 71 a 1,and thus, the cylindrical portion 61 can be more easily assembled.

Incidentally, it is preferable to form a tapered surface on an outeredge 73 e in an end portion along the axial direction of each roller 73of the one-way clutch 7 so as to be easily positioned against thetapered surface 61 b in assembling the cylindrical portion 61. Besides,when a tapered surface or an R surface is formed on the outercircumferential surface in an end portion along the axial direction ofthe shaft portion 51 and the inner circumferential surfaces in endportions along the axial direction of the inner rings 71 and 81 to befit on the shaft portion 51, the alignment and the assembly of these canbe easily performed.

Ultimately, as illustrated in FIG. 10(d), the key 53 is attached to thekeyway 51 b of the shaft portion 51, and the flange portion 52 a is fiton the outer circumferential surface 51 a of the shaft portion 51.

Incidentally, as the assembly method for the one-way clutch 7, a methodin which one of the rolling bearings 8 is first mounted to the outercircumference of the shaft portion 51 of the input rotating body 5, thecylindrical portion 61 of the output rotating body 6 is then mounted,and the one-way clutch assembled in advance is inserted between theshaft portion 51 and the cylindrical portion 61 may be employed. Sincethe one-way clutch used in the wind power generation device 1 is large,however, it is extremely difficult to insert the one-way clutchassembled in advance into a small space between the shaft portion 51 andthe cylindrical portion 61. In addition, each roller 73 protrudesradially outward beyond the inner circumferential surface 72 a of thecylindrical portion 61 owing to the action of the elastic member 75 andthe cam surface 71 a 1, and therefore, it is necessary to press eachroller 73 radially inward for inserting the one-way clutch 7 inside thecylindrical portion 61, which makes the assembly operation extremelycomplicated.

In contrast, in the assembly method of the present embodiment describedwith reference to FIGS. 10(a) to 10(d), the output rotating body 6 ismounted to the one-way clutch 7 and the rolling bearings 8, excludingthe outer rings 72 and 82, attached to the shaft portion 51 of the inputrotating body 5, and during this assembly, the plural rollers 73 can besimultaneously moved back radially inward by rotating the cylindricalportion 61 of the output rotating body 6, and thus, the shaft couplingdevice 9 can be easily assembled.

Incidentally, in the large-scaled wind power generation device 1 havinga rated output exceeding 1 MW, the shaft diameters of the output shaft35 of the speed-up gear 3 and the drive shaft 41 of the power generator4 are also large, and the weight of the shaft coupling device 9 isconsequently large. Accordingly, it is extremely difficult to performthe assembly operation by directly manually holding the components inassembling the shaft coupling device 9. In the wind power generationdevice 1 including the power generator 4 of, for example, 2 MW class,the weight of the shaft coupling device 9 exceeds 100 kg in some cases,and the labor necessary for the assembly operation, such as attaching acraned component in an unstable state and using a special jig, isextremely large. Therefore, it is extremely effective to assemble theshaft coupling device 9 as described above.

Incidentally, the assembly procedures up to FIG. 10(c) can beappropriately changed. For example, the inner ring 81, the cage 84 andthe cylindrical rollers 83 of the rolling bearing 8 can be respectivelyindividually attached to the shaft portion 51.

As illustrated in FIG. 2, the wind power generation device 1 of thepresent embodiment is provided with a covering member (shielding means)92 covering the shaft coupling device 9. This covering member 92 is madeof an elastically deformable synthetic resin, rubber, or the like.Besides, as illustrated also in FIG. 3, the covering member 92 is formedin a cylindrical shape, and includes connecting portions 93 and 94provided at both ends along the axial direction, and a bellows portion95 is provided between the connecting portions 93 and 94. One connectingportion 93 is fixed on the outer circumferential surface (or possibly onthe flange portion 41 a) of the drive shaft 41 with a fixing band or thelike. Besides, the other connecting portion 94 is connected by engagingwith the flange portion 35 c 1 of the output shaft 35. The bellowsportion 95 is expandable/contractible along the axial direction, andbendable or deformable along the radial direction.

FIG. 12 is an enlarged cross-sectional view of the connecting portion ofthe covering member.

The connecting portion 94 includes a core metal 94 a having an L-shapedcross section, and an elastic member 94 b adhering to the outer surfaceof the core metal 94 a. Besides, at the tip of the connecting portion94, a sliding member 94 c brought into contact with the side surface, ona side closer to the speed-up gear 3, of the flange portion 35 c 1 isprovided. This sliding member 94 c is made of a member having smallsliding friction against the flange portion 35 c 1, such as a memberobtained by coating a surface of a metal plate for lowering a frictioncoefficient. Besides, the sliding member 94 c is pressed against theflange portion 35 c 1 by a force caused when the bellows portion 95contracts in a direction of an arrow c, and the sealing action of thissliding member 94 c inhibits the flow of air coming into and going outof the covering member 92.

The wind power generation device 1 installed on the coast or offshore isoperated by receiving wind containing a large amount of a salt content,and if an outside air flow enters equipment housed in the nacelle 13,there arises a problem of metal corrosion due to a salt damage, whichlargely affects the durability. In the wind power generation device 1 ofthe present embodiment, the shaft coupling device 9 is covered by thecovering member 92, so as to inhibit foreign matters and an air flowfrom entering the shaft coupling device 9. Therefore, the functionaldeterioration of the shaft coupling device 9 caused by a salt damage orthe like, in particular, the functional deterioration of the one-wayclutch 7 can be prevented.

Besides, the covering member 92 is fixed, with its one end along theaxial direction, on the drive shaft 41, for example, relativelyunrotatably, but the other end thereof along the axial direction isconnected to the output shaft 35 relatively rotatably, and therefore,the covering member 92 is prevented from being twisted by the relativerotation of the output shaft 35 and the drive shaft 41 caused by theone-way clutch 7. Furthermore, the sliding member 94 c of the connectingportion 94 is pressed against the flange portion 35 c 1 by utilizing theelastic deformation (contraction) of the bellows portion 95, andtherefore, the relative rotation of these shafts can be allowed whileinhibiting the entrance of foreign matters and an air flow.

According to the wind power generation device 1 of the presentembodiment, if the rotational speed of the input rotating body 5 becomeslower than the rotational speed of the output rotating body 6, theconnection between the input rotating body 5 and the output rotatingbody 6 can be broken by the one-way clutch 7, which is disposed betweenthe input rotating body 5 rotating integrally with the output shaft 35of the speed-up gear 3 and the output rotating body 6 rotatingintegrally with the drive shaft 41 of the power generator 4. In otherwords, even if the rotational speed of the output shaft 35 is abruptlylowered via the main shaft 2 due to lowering of the wind force, theinertial rotation of the rotor 42 of the power generator 4 can beprevented from being transmitted to the output shaft 35 via the driveshaft 41. As a result, the reduction of a radial load applied to theroller bearing 38 supporting the output shaft 35 and the rotation delayof the cylindrical roller 38 c accompanying the reduction can besuppressed. Accordingly, if the rotational speed of the main shaft 2 isabruptly increased from this state due to change of the wind force andhence a high load is applied to the cylindrical roller 38 c, thecylindrical roller 38 c is difficult to slide on the contact surface incontact with the inner ring 38 a, and thus, the occurrence of thesmearing in the roller bearing 38 can be effectively suppressed.

Furthermore, since the inertial rotation of the rotor 42 is preventedfrom being transmitted to the output shaft 35, loads applied to theroller bearings 36 a, 36 b, 37 a, 37 b, 38, 39 and the like of thespeed-up gear 3 can be reduced. As a result, the sizes of all of thegears 31 b and 31 c of the planetary gear system 31, the shafts 33 to 35of the high-speed stage gear system 32 and the roller bearings 36 a, 36b, 37 a, 37 b, 38 and 39 can be reduced, and hence the speed-up gear 3can be reduced in its weight and can be produced at low cost.

Besides, since the connection between the input rotating body 5 and theoutput rotating body 6 is broken, the rotor 42 of the power generator 4continuously rotates due to inertia without abruptly lowering itsrotational speed, and hence, the average rotational speed of the rotor42 can be increased. As a result, the power generation efficiency of thepower generator 4 can be improved.

In addition, since the rolling bearings 8 are disposed between the inputrotating body 5 and the output rotating body 6 for relatively rotatablysupporting these rotors, if a gap is formed between the roller 73 andthe inner and outer rings 71 and 72 in the wedge-shaped space S becausethe engagement between the roller 73 and the inner and outer rings 71and 72 is released in the one-way clutch 7, the rolling bearings 8prevent the input rotating body 5 and the output rotating body 6 frommoving relatively along the radial direction. Accordingly, during theoperation of the wind power generation device 1, the input rotating body5 and the output rotating body 6 can be prevented from wobbling in theradial direction.

Besides, the outer ring inner circumferential surface 72 a of theone-way clutch 7 and the outer ring raceway surfaces 82 a of the rollingbearings 8 are formed on the inner circumferential surface of thecylindrical portion 61 of the output rotating body 6 serving as a commonmember. Therefore, the output rotating body 6 can work both as the outerring 72 of the one-way clutch 7 and the outer ring 82 of each rollingbearing 8. Thus, the structure of the whole wind power generation device1 can be simplified.

Furthermore, the output rotating body 6 is fixed removably on the driveshaft 41 of the power generator 4 and is disposed movably along theaxial direction against the input rotating body 5, and therefore, theoutput rotating body 6 can be removed from the input rotating body 5 byremoving the output rotating body 6 from the drive shaft 41 and movingit along the axial direction against the input rotating body 5. As aresult, the outer ring 72 of the one-way clutch 7 and the outer rings 82of the rolling bearings 8 can be simultaneously removed, and hence, amaintenance operation for the one-way clutch 7 and the rolling bearings8 can be easily performed. At this point, there is no need to move thepower generator 4, and hence the maintenance operation can be moreeasily performed.

As illustrated in FIG. 5, the input rotating body 5 and the outputrotating body 6 are allowed to relatively move along the axialdirection, for example, because the spaces s2 and s3 are provided,because the engaging element 73 of the one-way clutch 7 and the rollingelement 83 of the rolling bearing 8 are formed as cylindrical rollers,and because the outer ring inner circumferential surface 72 a and theouter ring raceway surface 82 a on which the cylindrical rollers 73 and83 move by rolling are formed as cylindrical surfaces (arc surfaces).Therefore, even when the output shaft 35 and the drive shaft 41 areexpanded/contracted along the axial direction (namely, the distancetherebetween along the axial direction is varied) due to the change inambient conditions, such as temperature change, theexpansion/contraction can be absorbed by the relative movement along theaxial direction of the input rotating body 5 and the output rotatingbody 6. As a result, a load along the axial direction can be inhibitedfrom being applied to the members supporting the output shaft 35 and thedrive shaft 41 (such as the rolling bearings and the like).

Besides, if the outer ring inner circumferential surface 72 a of theone-way clutch 7 and the outer ring raceway surfaces 82 a of the rollingbearings 8 are moved against the cylindrical rollers 73 and 83 along theaxial direction due to the relative movement along the axial directionof the input rotating body 5 and the output rotating body 6, the outerring inner circumferential surface 72 a and the outer ring racewaysurface 82 a are substantially positionally shifted along the axialdirection. In particular, since the wind power generation device 1 has alarge size, the positional shift is inevitably large. In order to copewith such a positional shift, the inner circumferential surface of thecylindrical portion 61 is preferably, in advance, subjected to a surfacetreatment necessary for the outer ring cylindrical surface 72 a and theouter ring raceway surface 82 a over a range covering a conceivablepositional shift. Incidentally, this positional shift can be estimatedby obtaining, by calculation or experiment, expansion/contraction of therespective members within a temperature change region (of, for example,−40° C. to 60° C.) assumed on the basis of the environment temperatureat which the wind power generation device 1 is used, the temperaturewithin the nacelle estimated in consideration of the amount of heatgenerated by the power generator 4, and the like. Besides, the spaces s2and s3 are preferably set to be larger than the amount of the expansionalong the axial direction of each shaft expected at the upper limit (thehighest temperature) of the assumed temperature change region.Furthermore, the surface treatment for the outer ring innercircumferential surface 72 a and the outer ring raceway surface 82 a maybe, for example, a surface modifying treatment such as a carbonitridingtreatment, or a coating treatment such as a blackening treatment or DLCcoating. Alternatively, it may be a heat treatment such as quenching ortempering.

As illustrated in FIG. 2, if the brake 44 for braking the drive shaft 41is provided, the one-way clutch 7 or the shaft coupling device 9including it is preferably disposed between the speed-up gear 3 and thebrake 44. In the case where the one-way clutch 7 is disposed, forexample, between the brake 44 and the power generator 4, even if thebrake 44 is operated during the rotation, merely the rotation on theside of the speed-up gear 3 is lowered in speed, but the rotation on theside of the power generator 4 is continued by the one-way clutch 7 to beidled, and it is difficult to rapidly stop the power generator 4 at thetime of, for example, occurrence of abnormality of the power generator4.

It is not always necessary, however, to provide the one-way clutch 7 orthe shaft coupling device 9 between the brake 44 and the power generator4, but it may be provided between the brake 44 and the power generator 4as illustrated in FIG. 16. Besides, if a brake for the output shaft 35and a brake for the drive shaft 41 are respectively provided, theone-way clutch 7 and the shaft coupling device 9 may be provided betweenthese brakes.

FIG. 13 is a cross-sectional view of a shaft coupling device accordingto a second embodiment of the present invention, and FIG. 14 is anenlarged cross-sectional view of a principal part of a one-way clutch 7of FIG. 13.

The shaft coupling device 9 of the present embodiment uses a sprag as anengaging element 73. Besides, an inner ring of the one-way clutch 7 isformed by a shaft portion 51 of an input rotating body 5, and an outercircumferential surface 71 a of the inner ring is formed by an outercircumferential surface 51 a of the shaft portion 51. The inner ringouter circumferential surface 71 a is formed as a cylindrical surfacewithout forming a cam surface as in the first embodiment.

Besides, an inner ring of a rolling bearing 8 is also formed by theshaft portion 51 of the input rotating body 5, and an outercircumferential surface 81 a of the inner ring is formed by the outercircumferential surface 51 a of the shaft portion 51.

One ring portion 76 of a cage 74 of the one-way clutch 7 has a ridgeportion 76 b protruding radially outward. This ridge portion 76 b isslidably fit in a circumferential groove 61 c 1 formed on an innercircumferential surface of a cylindrical portion 61 of an outputrotating body 6, so as to regulate the position along the axialdirection of the cage 74.

Similarly, one ring portion 86 of a cage 84 of the rolling bearing 8 hasa ridge portion 86 b protruding radially outward. This ridge portion 86b is slidably fit in a circumferential groove 61 c 2 formed on the innercircumferential surface of the cylindrical portion 61, so as to regulatethe position along the axial direction of the cage 84.

The sprag 73 includes a first contact surface 73 b coming into contactwith the outer circumferential surface 51 a of the shaft portion 51 (theinner ring outer circumferential surface 71 a), and a second contactsurface 73 c coming into contact with an inner circumferential surface72 a of an outer ring 72 (the cylindrical portion 61), and each of thefirst contact surface 73 b and the second contact surface 73 c is formedin a projecting and substantially arc shape. Besides, a distance betweenthe first contact surface 73 b and the second contact surface 73 crespectively in contact with the outer circumferential surface 51 a ofthe shaft portion 51 and the outer ring inner circumferential surface 72a is changed in accordance with the inclination of the sprag 73, andwhen the shaft portion 51 is rotated in a direction of an arrow a, thesprag 73 inclines in a direction of an arrow e, and hence the distancebetween the first contact surface 73 b and the second contact surface 73c is increased. On the contrary, when the shaft portion 51 is rotated ina direction of an arrow b, the sprag 73 inclines in an oppositedirection to the arrow e, and hence the distance between the firstcontact surface 73 b and the second contact surface 73 c is reduced.

When the distance between the first contact surface 73 b and the secondcontact surface 73 c is increased, the sprag 73 engages the outercircumferential surface 51 a of the shaft portion 51 and the innercircumferential surface 72 a of the outer ring 72, and on the contrary,when the distance between the first contact surface 73 b and the secondcontact surface 73 c is reduced, the engagement of the sprag 73 with theouter circumferential surface 51 a of the shaft portion 51 and the innercircumferential surface 72 a of the outer ring 72 is released.Accordingly, when the shaft portion 51 is to relatively rotate in thedirection of the arrow a against the outer ring 72, the shaft portion 51and the outer ring 72 are integrally rotatably connected to each other,and when the shaft portion 51 relatively rotates in the direction of thearrow b against the outer ring 72, the connection between the shaftportion 51 and the outer ring is broken.

In the present embodiment, the same effects as those of the firstembodiment can be attained, and in addition, since there is no need toform a cam surface on the inner ring of the one-way clutch 7 (the shaftportion 51), the production cost can be reduced. Besides, since theshaft portion 51 can be used as the inner ring, the production cost canbe further reduced, and in addition, the structure of the one-way clutch7 can be simplified and its diameter can be reduced. Furthermore, thetorque capacity can be more easily increased by increasing the rigidityin using the sprag 73 than in using a roller, and therefore, thedimensions along the radial direction and the axial direction of thesprag 73 itself can be reduced. Accordingly, the dimensions along theradial direction and the axial direction of the one-way clutch 7 can bereduced to attain compactness. When the one-way clutch 7 is thus madecompact, the shaft coupling device 9 can be made compact as a wholealong the radial direction and the axial direction. As a result, even ifa space between an output shaft 35 of a speed-up gear 3 and a driveshaft 41 of a power generator 4 is small, the shaft coupling device 9can be suitably provided.

Incidentally, in the second embodiment, the sprag 73 and a cylindricalroller 83 are movable along the axial direction on the outercircumferential surface 51 a of the shaft portion 51, and therefore, theinput rotating body 5 and the output rotating body 6 are allowed torelatively move along the axial direction. Besides, this relativemovement shifts the positions along the axial direction of the innerring outer circumferential surface 71 a and the inner ring racewaysurface 81 a corresponding to the sprag 73 and the cylindrical roller83, and hence, the inner ring outer circumferential surface 71 a and theinner ring raceway surface 81 a are preferably subjected to a necessarysurface treatment (such as a surface modifying treatment, a coatingtreatment or a heat treatment) over a range covering a conceivablepositional shift.

Furthermore, in the second embodiment, the inner ring may be fit on theouter circumferential surface of the shaft portion 51 with the sprag 73engaged with the outer circumferential surface of the inner ring. Inthis case, the shaft portion 51 and the inner ring are preferably fit bythe interference fit so as to satisfy the conditions (1) to (3)described above.

The present invention is not limited to the aforementioned embodimentsbut can be practiced with appropriate modification.

For example, although the output rotating body 6 is provided radiallyoutside the input rotating body 5, it may be provided radially insidethe input rotating body 5 as illustrated in FIG. 18. Specifically, theoutput rotating body 6 may be provided with a shaft portion 65 and theinput rotating body 5 may be provided with a cylindrical portion 54, sothat the cylindrical portion 54 can be coaxially provided radiallyoutside the shaft portion 65. Besides, the inner circumferential surfaceof the cylindrical portion 54 may be formed as the outer ring innercircumferential surface of the one-way clutch 7 and the outer ringraceway surfaces of the rolling bearings 8, so that the inner rings 71and 81 of the one-way clutch 7 and the rolling bearings 8 can be fit onthe shaft portion 65 of the output rotating body 6.

Furthermore, in this case, the outer ring inner circumferential surfaceof the one-way clutch 7 may be formed as a cam surface, and the innerring outer circumferential surface may be formed as a cylindricalsurface. In addition, in this case, the inner ring outer circumferentialsurface may be formed on the outer circumferential surface of the shaftportion 65 of the output rotating body 6, so as to use the shaft portion65 also as the inner ring.

Moreover, although the output rotating body is used as the outer ring ofthe one-way clutch and the outer rings of the rolling bearings, theseouter rings may be provided on the output rotating body as separatemembers.

Besides, although each rolling bearing provided between the inputrotating body and the output rotating body is a cylindrical rollerbearing for moving the output rotating body along the axial direction,it may be a ball bearing if the output rotating body is not moved alongthe axial direction.

The ring portions and the pillar portions of the cage of the one-wayclutch may be integrally formed by using the same material, and thematerial may be a metal or a synthetic resin. As the synthetic resinmaterial used for forming the cage, a phenol resin, a polyamide resin, aPEEK (polyether ether ketone) resin or the like can be used.

The wind power generation device 1 of the present invention is notlimited to the horizontal axis type illustrated in FIG. 1 but may be avertical axis type illustrated in FIG. 15. Also in this case, the shaftcoupling device 9 including the one-way clutch can be provided betweenthe speed-up gear 3 and the power generator 4.

The covering member 103 included in the sealing means 10 may be attachedto the shaft portion 51 of the input rotating body 5 with a fixing screw103 b as illustrated in FIG. 17. In this case, the covering member 103not only forms the sealing means 10 but also functions as a “shiftpreventing member” for preventing the shift along the axial directionbetween the input rotating body 5 and the output rotating body 6. Sincesuch a shift preventing member 103 is provided, the input rotating body5 and the output rotating body 6 can be prevented from separating fromeach other when, for example, the shaft coupling device 9 is mountedbetween the speed-up gear 3 and the power generator 4, or when the shaftcoupling device 9 is craned in transporting it for shipping. Besides, ifmerely the function as the shift preventing member is necessary, thesealing member 104 can be omitted.

The present invention is not limited to the structure in which theoutput shaft 35 of the speed-up gear 3 and the drive shaft 41 of thepower generator 4 are connected via the shaft coupling device 9, but mayemploy a structure in which the one-way clutch 7 is directly mountedbetween the output shaft 35 and the drive shaft 41.

Furthermore, the output shaft 35 of the embodiment of the presentinvention may embrace a portion of the shaft coupling device 9 connectedto the output shaft 35, and similarly, the drive shaft 41 may embrace aportion of the shaft coupling device 9 connected to the drive shaft 41.

Now, a third embodiment of the present invention will be described withreference to the accompanying drawings. In the present embodiment, likereference numerals are used to refer to like or similar elements tothose used in the first and second embodiments, so as to omit thedetailed description.

FIG. 19 is a schematic side view of a wind power generation deviceaccording to the third embodiment of the present invention. This windpower generation device (power generation device) 100 includes a mainshaft 2 rotated by receiving a wind force (an external force), aspeed-up gear 3 connected to the main shaft 2, and a power generator 4connected to the speed-up gear 3, and the power generator 4 is drivenwith the rotation of the main shaft 2 increased in speed by the speed-upgear 3.

At the tip of the main shaft 2, a wind turbine 113 having, for example,a blade (not shown) is integrally rotatably connected, and the windturbine 113 rotates together with the main shaft 2 by receiving the windforce with the blade.

The power generator 4 includes a drive shaft 41 rotated by receiving therotation increased in speed by the speed-up gear 3, a rotor 42 housed ina casing 4 a of the power generator 4, and a stator and the like notshown. The rotor 42 is integrally rotatably connected to the drive shaft41, and power is generated by rotating the rotor 42 together with thedrive shaft 41.

In FIG. 19, the wind power generation device 100 further includes aninput rotating body 105 integrally rotatably provided on an output shaft35 of the speed-up gear 3, an output rotating body 106 integrallyrotatably provided on the drive shaft 41 of the power generator 4, aone-way clutch 107 and an electromagnetic clutch (connecting means) 109disposed between the input rotating body 105 and the output rotatingbody 106, and a pair of rolling bearings 108 disposed on both sidesalong the axial direction of the one-way clutch 107.

The one-way clutch 107 and the electromagnetic clutch 109 transmit therotation of the output shaft 35 to the drive shaft 41 via the inputrotating body 105 and the output rotating body 106. The electromagneticclutch 109 is supported by a housing 111. Besides, the electromagneticclutch 109 can be operated mainly when the power generator 4 is to bestopped without connecting the input rotating body 105 and the outputrotating body 106 during a normal operation of the power generator 4.The electromagnetic clutch 109 will be described in detail later. Therolling bearings 108 are disposed on both sides along the axialdirection of the one-way clutch 107, but the rolling bearing may bedisposed on merely one side along the axial direction of the one-wayclutch 107.

FIG. 20 is a cross-sectional view illustrating a connecting portionbetween the output shaft 35 of the speed-up gear 3 and the drive shaft41 of the power generator 4, particularly illustrating the structures ofthe one-way clutch 107 and the rolling bearing 108 in detail.Accordingly, in this drawing, the electromagnetic clutch 109 is omitted.Besides, FIG. 22 is a schematic cross-sectional view of the connectingportion between the output shaft 35 and the drive shaft 41, particularlyillustrating the structures of the one-way clutch 107, the rollingbearing 108 and the electromagnetic clutch 109. In FIGS. 20 and 22, theinput rotating body 105 is disposed coaxially with the output shaft 35.Besides, the input rotating body 105 has a flange portion 151, a largediameter portion 152, a spline portion 154 and a small diameter portion153 arranged in this order from a first end portion (a left end portionin FIG. 22) to a second end portion (a right end portion in FIG. 22)thereof along the axial direction.

The flange portion 151 is formed to extend radially outward beyond theouter circumferential surface of the large diameter portion 152, and isremovably fixed on an output end portion 35 c of the output shaft 35.Specifically, the flange portion 151 is in contact with a flange portion35 c 1 formed on the output end portion 35 c to be fastened and fixed onthe flange portion 35 c 1 with a bolt and a nut not shown. Asillustrated in FIG. 20, a space S1 is formed between an end surface ofthe small diameter portion 153 and an end surface of a flange portion 41a of the drive shaft 41.

The output rotating body 106 is coaxially disposed radially outside theinput rotating body 105, and has a cylindrical portion 161 and a flangeportion 162 formed on a second end portion (a right end portion in FIG.20) along the axial direction of the cylindrical portion 161.

The flange portion 162 is formed to extend radially outward beyond theouter circumferential surface of the cylindrical portion 161, and isremovably fixed in a first end portion of the drive shaft 41.Specifically, the flange portion 162 is in contact with the flangeportion 41 a formed in the first end portion of the drive shaft 41 to befastened and fixed on the flange portion 41 a with a bolt and a nut notshown.

The inner circumferential surface of the cylindrical portion 161 isformed as a cylindrical surface, and in a space between the innercircumferential surface of a first end (a left end in FIG. 20) along theaxial direction of the cylindrical portion 161 and the outercircumferential surface of the input rotating body 105, a ring-shapedsealing member 110 for sealing a ring-shaped space formed between thecylindrical portion 161 and the input rotating body 105 is provided.With the output rotating body 106 separated from the drive shaft 41, theoutput rotating body 106 can be moved along the axial direction againstthe input rotating body 105.

FIG. 21 is a cross-sectional view of the one-way clutch 107. In FIGS. 20and 21, the one-way clutch 107 includes an inner ring 171, an outer ring172, and a plurality of rollers 173 disposed between an outercircumferential surface 171 a of the inner ring 171 and an innercircumferential surface 172 a of the outer ring 172.

The inner ring 171 is fit and fixed on a center portion along the axialdirection of the small diameter portion 153 of the input rotating body105, so as to rotate integrally with the small diameter portion 153. Aregion B of a center portion along the axial direction of thecylindrical portion 161 of the output rotating body 106 corresponds tothe outer ring 172 of the one-way clutch 107. Accordingly, the innercircumferential surface 172 a is formed on the inner circumference ofthe region B of the cylindrical portion 161. Each roller 173 is in acylindrical shape and is provided in number of eight arranged along thecircumferential direction in this embodiment.

The one-way clutch 107 further includes a ring-shaped cage 174 forholding the respective rollers 173 at prescribed intervals along thecircumferential direction, and a plurality of elastic members 175elastically pressing the rollers 173 in one direction.

The cage 174 includes a pair of ring portions 174 a opposing each otheralong the axial direction, and a plurality of pillar portions 174 bextending along the axial direction between the ring portions 174 a andarranged at equal intervals along the circumferential direction toconnect the ring portions 174 a. A plurality of pockets 174 c are formedbetween the ring portions 174 a and the pillar portions 174 b adjacentto each other, and each of the rollers 173 is individually held in eachpocket 174 c.

The elastic member 175 is made of a compression coil spring, and is heldin each of the pockets 174 c of the cage 174 to be attached to thecorresponding pillar portion 174 b.

In FIG. 21, flat cam surfaces 171 a 1 in the same number as the rollers173 (namely, eight) are formed on the outer circumferential surface 171a of the inner ring 171, and the inner circumferential surface 172 a ofthe outer ring 172 is formed as a cylindrical surface. Between the camsurfaces 171 a 1 of the inner ring 171 and the cylindrical surface ofthe outer ring 172, a plurality of (eight) wedge-shaped spaces S2 areformed along the circumferential direction. The rollers 173 areindividually disposed respectively in the wedge-shaped spaces S2, andeach elastic member 175 presses the corresponding roller 173 toward adirection where the wedge-shaped space S2 becomes smaller. The outercircumferential surface of each roller 173 works as a contact surface173 a to be brought into contact with the cam surface 171 a 1 of theinner ring 171 and the cylindrical surface of the outer ring 172, andthe contact surface 173 a is formed to be straight (parallel to thecenter of the roller) in the width direction (the axial direction).Incidentally, the one-way clutch 107 is in an environment where agrease, that is, a lubricant difficult to be affected by temperaturechange, containing a base oil of an ester and a urea-based thickener isprovided between the inner and outer rings 171 and 172.

In the one-way clutch 107 having the aforementioned structure, if theinput rotating body 105 rotates at an increasing speed and as a result,the rotational speed of the input rotating body 105 exceeds therotational speed of the output rotating body 106, the inner ring 171 isto rotate relatively against the outer ring 172 in a first direction(the counterclockwise direction in FIG. 21). In this case, the roller173 slightly moves, owing to the pressing force applied by the elasticmember 175, in the direction where the wedge-shaped space 2S becomessmaller, the contact surface 173 a of the roller 173 is pressed againstthe outer circumferential surface 171 a of the inner ring 171 and theinner circumferential surface 172 a of the outer ring 172, and hence,the one-way clutch 107 is placed in a state where the roller 173 isengaged with the inner and outer rings 171 and 172. As a result, theinner and outer rings 171 and 172 can integrally rotate in the firstdirection, and hence, the input rotating body 105 and the outputrotating body 106 can be integrally rotatably connected to each other.

Besides, if the input rotating body 105 rotates at a constant speedafter rotating at an increasing speed and as a result, the rotationalspeed of the input rotating body 105 becomes the same as the rotationalspeed of the output rotating body 106, the roller 173 is held in a statewhere it is engaged with the inner and outer rings 171 and 172.Therefore, the one-way clutch 107 retains the integral rotation in theabove-described first direction of the inner and outer rings 171 and172, and hence, the input rotating body 105 and the output rotating body106 continues to integrally rotate.

On the other hand, if the input rotating body 105 rotates at adecreasing speed and as a result, the rotational speed of the inputrotating body 105 becomes lower than the rotational speed of the outputrotating body 106, the inner ring 171 is to rotate relatively againstthe outer ring 172 in a second direction (the clockwise direction ofFIG. 21). In this case, the roller 173 slightly moves, against thepressing force applied by the elastic member 175, in a direction wherethe wedge-shaped space 2S becomes larger, and thus, the engagementbetween the roller 173 and the inner and outer rings 171 and 172 isreleased. Since the engagement of the roller 173 is thus released, theconnection between the input rotating body 105 and the output rotatingbody 106 is broken.

In FIG. 20, the pair of rolling bearings 108 are disposed between thesmall diameter portion 153 of the input rotating body 105 and thecylindrical portion 161 of the output rotating body 106, so as torelatively rotatably support the input rotating body 105 and the outputrotating body 106. Besides, the rolling bearings 108 are disposedrespectively adjacent on both sides along the axial direction of theone-way clutch 107 so that their end portions along the axial directioncan come into contact with the end surfaces along the axial direction ofthe cage 174 of the one-way clutch 107.

The rolling bearing 108 is formed by a cylindrical roller bearingincluding an inner ring 181, an outer ring 182, and a plurality ofcylindrical rollers 183 disposed between the inner ring 181 and theouter ring 182 to be movable by rolling.

The inner ring 181 includes an inner ring raceway surface 181 a formedon the outer circumference, and inner ring flange portions 181 bprotruding radially outward on both sides along the axial direction ofthe inner ring raceway surface 181 a. Both the end surfaces of eachcylindrical roller 183 are in sliding contact respectively with theinner side surfaces of the respective inner ring flange portions 181 b.Besides, an outer side surface 181 b 1 of the inner ring flange portion181 b adjacent to the one-way clutch 107 is formed as a contact surfaceto be in contact with the outer side surface of the ring portion 174 acorresponding to the end surface along the axial direction of the cage174 of the one-way clutch 107.

A region A and a region C of both end portions along the axial directionof the cylindrical portion 161 of the output rotating body 106correspond to the outer rings 182 of the rolling bearings 108, and outerring raceway surfaces 182 a of the outer rings 182 are respectivelyformed on the inner circumferential surfaces of the regions A and C.Between the outer ring raceway surface 182 a and the inner ring racewaysurface 181 a, the cylindrical roller 183 is disposed to be movable byrolling.

In this wind power generation device 100, if the rotational speed of theinput rotating body 105 becomes lower than the rotational speed of theoutput rotating body 106, the connection between the input rotating body105 and the output rotating body 106 can be broken by the one-way clutch107, which is disposed between the input rotating body 105 rotatingintegrally with the output shaft 35 of the speed-up gear 3 and theoutput rotating body 106 rotating integrally with the drive shaft 41 ofthe power generator 4. In other words, even if the rotational speed ofthe output shaft 35 is abruptly lowered via the main shaft 2 due tolowering of the wind force, the inertial rotation of the rotor 42 of thepower generator 4 can be prevented from being transmitted to the outputshaft 35 via the drive shaft 41. As a result, the reduction of a radialload applied to the roller bearing 38 supporting the output shaft 35 andthe rotation delay of the cylindrical roller 38 c accompanying thereduction can be suppressed. Accordingly, if the rotational speed of themain shaft 2 is abruptly increased from this state due to change of thewind force and hence a high load is applied to the cylindrical roller 38c, the cylindrical roller 38 c is difficult to slide on the contactsurface in contact with the inner ring 38 a, and thus, the occurrence ofthe smearing in the roller bearing 38 can be effectively suppressed.

Furthermore, since the inertial rotation of the rotor 42 is preventedfrom being transmitted to the output shaft 35, loads applied to theroller bearings 36 a, 36 b, 37 a, 37 b, 38, 39 and the like of thespeed-up gear 3 can be reduced. As a result, the sizes of all of thegears 31 b and 31 c of the planetary gear system 31, the shafts 33 to 35of the high-speed stage gear system 32 and the roller bearings 36 a, 36b, 37 a, 37 b, 38 and 39 can be reduced, and hence the speed-up gear 3can be reduced in its weight and can be produced at low cost.

Besides, since the connection between the input rotating body 105 andthe output rotating body 106 is broken, the rotor 42 of the powergenerator 4 continuously rotates due to inertia without abruptlylowering the rotational speed, and hence, the average rotational speedof the rotor 42 can be increased. As a result, the power generationefficiency of the power generator 4 can be improved.

In addition, since the rolling bearings 108 are disposed between theinput rotating body 105 and the output rotating body 106 for relativelyrotatably supporting these rotors, if a gap is formed between the roller173 and the inner and outer rings 171 and 172 in the wedge-shaped space2S because the engagement between the roller 173 and the inner and outerrings 171 and 172 is released in the one-way clutch 107, the rollingbearings 108 can prevent the input rotating body 105 and the outputrotating body 106 from moving relatively along the radial direction.Accordingly, during the operation of the wind power generation device100, the input rotating body 105 and the output rotating body 106 can beprevented from wobbling in the radial direction.

Besides, since the pair of rolling bearings 108 are disposedrespectively adjacent on both sides along the axial direction of theone-way clutch 107 so that their end portions along the axial directioncan come into contact with the end surfaces along the axial direction ofthe cage 174 of the one-way clutch 107, the movement of the cage 174along the axial direction can be regulated by causing the end surfacesalong the axial direction of the cage 174 to come into contact with theend portions along the axial direction of the rolling bearings 108.

Furthermore, since the end surface along the axial direction of the cage174 of the one-way clutch 107 (the outer side surface of the ringportion 174 a) is brought into contact with the inner ring flangeportion 181 b of the rolling bearing 108, the inner ring flange portion181 b of the rolling bearing 108 can be used also as a member forregulating the movement along the axial direction of the cage 174. Thus,the structure of the rolling bearing 108 can be simplified.

Besides, since the outer ring inner circumferential surface 172 a of theone-way clutch 107 and the outer ring raceway surfaces 182 a of therolling bearings 108 are formed on the inner circumferential surface ofthe output rotating body 106, the output rotating body 106 can be usedboth as the outer ring 172 of the one-way clutch 107 and the outer ring182 of each rolling bearing 108. Thus, the structure of the whole windpower generation device 100 can be simplified.

Moreover, the inner circumferential surface of the output rotating body106 including the outer ring inner circumferential surface 172 a and theouter ring raceway surface 182 a is formed to have a prescribed innerdiameter, and the output rotating body 106 is removably fixed on thedrive shaft 41 of the power generator 4, and is disposed movably alongthe axial direction against the input rotating body 105. Therefore, theoutput rotating body 106 can be removed from the input rotating body 105by removing the output rotating body 106 from the drive shaft 41 andmoving it along the axial direction against the input rotating body 105.As a result, the outer ring 172 of the one-way clutch 107 and the outerrings 182 of the rolling bearings 108 can be simultaneously removed, andhence, a maintenance operation for the one-way clutch 107 and therolling bearings 108 can be easily performed. At this point, there is noneed to move the power generator 4, and hence the maintenance operationcan be more easily performed.

Next, the structure and the control of the electromagnetic clutch 109will be described in detail.

As illustrated in FIG. 22, the electromagnetic clutch 109 serves asconnecting means for connecting (coupling) the input rotating body 105connected to the output shaft 35 and the output rotating body 106connected to the drive shaft 41 to each other in aconnectable/disconnectable manner. This electromagnetic clutch 109 iswhat is called a friction type clutch, and includes a first clutchmember 191 and a second clutch member 192 mutually frictionallyconnected, and a clutch coil 193. The first clutch member 191 includes afirst disk portion 191 a formed in a disk shape of a steel material, anda first cylindrical portion 191 b provided radially inside the firstdisk portion 191 a, and this first cylindrical portion 191 b is splinefit in the spline portion 154 of the input rotating body 105, so thatthe first clutch member 191 can be attached to the input rotating body105 so as to be integrally rotatable and movable along the axialdirection.

The second clutch member 192 includes a second disk portion 192 a formedin a disk shape, and a second cylindrical portion 192 b providedradially inside the second disk portion 192 a, and this secondcylindrical portion 192 b is integrally rotatably fit on the outercircumferential surface of the output rotating body 106.

The clutch coil 193 is held in a coil holder 194 and disposed behind thesecond disk portion 192 a, namely, on the opposite side to the firstclutch member 191, so as to generate a magnetic force when power issupplied from a control unit 112 (see FIG. 19). The coil holder 194 issupported on its outer circumferential side by the housing 111, and thesecond clutch member 192 is rotatably connected via a bearing 195 on theinner circumferential side. When a magnetic power is generated in theclutch coil 193, the first clutch member 191 and the second clutchmember 192 move in directions where they come close to each other, andtheir disk portions 191 a and 192 a are pressed against each other to befrictionally connected to each other. In this manner, the input rotatingbody 105 and the output rotating body 106 are connected to each other,so that the rotation of the output shaft 35 can be transmitted to thedrive shaft 41.

The electromagnetic clutch 109 is controlled by the control unit 112 sothat the output shaft 35 and the drive shaft 41 can be connected to eachother when a prescribed condition is satisfied. Specifically, in thepresent embodiment, a prescribed condition is set as a condition forstopping the power generator 4. It is determined, by the control unit112 on the basis of a detection result of detection means for detectingvarious states of the wind power generation device 100, whether or notthe condition for stopping the power generator 4 is satisfied.

As illustrated in FIG. 19, a temperature sensor 121, that is, one of thedetection means, is provided inside the casing 4 a of the powergenerator 4. This temperature sensor 121 always detects the temperaturewithin the casing 4 a, and inputs a detection signal to the control unit112.

Besides, a vibration sensor 122, that is, one of the detection means, isprovided within or in the vicinity of the casing 4 a of the powergenerator 4. This vibration sensor 122 always detects the vibration ofthe casing 4 a, and inputs a detection signal to the control unit 112.

A power generation measuring device 124 for measuring the amount ofgenerated power is connected to the power generator 4. On the otherhand, a speed sensor 123 for detecting the rotational speed of theoutput shaft 35 is provided on the output shaft 35. The power generationmeasurement device 124 and the speed sensor 123 are also one of thedetection means, and an amount of generated power measured by the powergeneration measuring device 124 and a detection value of the speedsensor 123 are respectively input to the control unit 112.

Besides, in the wind power generation device 100 of the presentembodiment, separately from the detection means described above,accepting means 125 for accepting an input of an instruction to stop thepower generator 4 is provided. The accepting means 125 of the presentembodiment is provided as a stop switch for stopping the power generator4, and when this stop switch 125 is operated, a signal corresponding tothe operation is input to the control unit 112.

The control unit 112 controls the operation of the electromagneticclutch 109 on the basis of signals from the respective sensors 121 to123 and the measuring device 124 (hereinafter designated as the“sensors”) or a signal from the stop switch 125. Specifically, when itis determined, on the basis of a detection signal of the sensors, thatthe power generator 4 has a problem, the control unit 112 controls theelectromagnetic clutch 109 to connect the output shaft 35 and the driveshaft 41 to each other. Besides, in order to stop the power generator 4,the control unit 112 also performs control to stop the rotation of thewind turbine 113 to stop the external force supply to the main shaft 2.For example, the control unit 112 can stop the rotation of the windturbine 113 by controlling a pitch angle of the blade of the windturbine 113 to place it in a feathering state.

If the temperature within the casing 4 a of the power generator 4 isabnormally increased, it can be regarded that a problem such as aseizure has occurred in the casing 4 a. Therefore, the control unit 112determines whether or not a detection signal from the temperature sensor121 exceeds a prescribed threshold value (such as a temperature at whicha seizure or the like is liable to occur), and performs the control tostop the wind turbine 113 as well as controls the electromagnetic clutch109 to connect the output shaft 35 and the drive shaft 41 to each other.When the wind turbine 113 is stopped, the external force supply to themain shaft 2 is also stopped, and hence, the output shaft 35 of thespeed-up gear 3 stops after abrupt rotational speed lowering. Therefore,the rotational speed of the output shaft 35 becomes lower than therotational speed of the drive shaft 41 of the power generator 4, andhence the connection between the output shaft 35 and the drive shaft 41via the one-way clutch 107 is broken. At this point, if theelectromagnetic clutch 109 is not operated, even when the output shaft35 is stopped, the drive shaft 41 does not stop but continuously rotatesdue to the inertial force of the rotor 42, and hence the power generator4 cannot be rapidly stopped. In the present embodiment, however, theelectromagnetic clutch 109 is operated to connect the output shaft 35and the drive shaft 41 to each other, and therefore, not only the outputshaft 35 but also the drive shaft 41 can be stopped with the rotationalspeed abruptly lowered. At this point, the speed-up gear 3 works as abrake for the power generator 4, and thus, the power generator 4 can berapidly stopped.

Similarly, if the vibration of the power generator 4 is abnormallyincreased, it can be regarded that a problem such as a damage hasoccurred in a shaft or a bearing used in the power generator 4.Therefore, the control unit 112 determines whether or not a detectionsignal from the vibration sensor 122 exceeds a prescribed thresholdvalue, and if it does, performs the control to stop the wind turbine 113as well as controls the electromagnetic clutch 109 to connect the outputshaft 35 and the drive shaft 41 to each other.

Besides, also in the case where the amount of power generated by thepower generator 4 is small in terms of the rotational speed of theoutput shaft 35, it can be regarded that any problem has occurred in thepower generator 4. Therefore, the control unit 112 estimates a suitableamount of power generation on the basis of a detection signal from thespeed sensor 123, and compares the estimated amount with an outputsignal from the power generation measuring device 124. Then, it isdetermined whether or not a difference therebetween exceeds a prescribedthreshold value, and if it does, the control unit 112 performs thecontrol to stop the wind turbine 113 as well as controls theelectromagnetic clutch 109 to connect the output shaft 35 and the driveshaft 41 to each other.

Through the aforementioned control, the power generator 4 can beautomatically and rapidly stopped when the condition for stopping thepower generator 4 is satisfied. Therefore, the power generator 4 can beprevented from continuously working with a problem not settled.

Besides, in the present embodiment, the power generator 4 can be rapidlystopped by operating the stop switch 125. Accordingly, when an operationsuch as maintenance of the power generator 4 is to be performed, thepower generator 4 can be rapidly stopped for performing the operation.

The present invention is not limited to the aforementioned embodimentbut can be practiced with appropriate modification.

For example, as the connecting means for connecting the output shaft ofthe speed-up gear and the drive shaft of the power generator to eachother, means different from the electromagnetic clutch can be used. Whenthe electromagnetic clutch is used as the connecting means, however, theconnection of the output shaft and the drive shaft and the releasethereof can be rapidly and accurately switched. Besides, the connectingmeans may be any means as long as it can integrally rotatably connectthe output shaft and the drive shaft to each other at least in a secondstate where the rotational speed of the output shaft is lower than therotational speed of the drive shaft.

Instead of the speed sensor for detecting the rotational speed of theoutput shaft, a speed sensor for detecting the rotational speed of thedrive shaft or the main shaft may be provided. Besides, as the detectionmeans, at least some of the aforementioned sensors may be provided, oranother detection means may be provided.

Although the input rotating body and the output rotating body areprovided respectively as separate members from the output shaft and thedrive shaft in the present embodiment, these rotors may be formedintegrally respectively with the output shaft and the drive shaft.

Besides, although the output rotating body is disposed radially outsidethe input rotating body, it may be disposed radially inside the inputrotating body. In this case, the one-way clutch may have the outer ringinner circumferential surface formed as the cam surface and the innerring outer circumferential surface formed as the cylindrical surface.Furthermore, in this case, the inner ring outer circumferential surfacemay be formed on the outer circumferential surface of the outputrotating body, so as to use the output rotating body also as the innerring.

In other words, in the power generation device of the present invention,either of the structure in which the input rotating body is providedinside (on the side of the inner ring) with the output rotating bodyprovided outside (on the side of the outer ring) as in theaforementioned embodiment and the structure in which the input rotatingbody is provided outside (on the side of the outer ring) with the outputrotating body provided inside (on the side of the inner ring) may beemployed.

Furthermore, although the output rotating body is used as the outer ringof the one-way clutch and the outer rings of the rolling bearings, theseouter rings may be provided as members separate from the output rotatingbody.

Besides, each rolling bearing disposed between the input rotating bodyand the output rotating body is a cylindrical roller bearing for movingthe output rotating body in the axial direction, but if the outputrotating body is not moved in the axial direction, a ball bearing may beused.

Moreover, although the cage of the one-way clutch is in contact with theinner ring of the rolling bearing, the outer ring of the rolling bearingmay be provided as a member separate from the output rotating body, sothat the cage of the one-way clutch may be in contact with this outerring.

Furthermore, although the power generation device of the presentembodiment is described exemplarily on the assumption that the windforce is used as the external force, it can be applied to a powergeneration device for generating power by using another external forcesuch as a water force or a heat force.

The detection means may be a sensor (such as a state monitoring sensorlike a temperature sensor, a vibration sensor or the like) provided inthe vicinity of the one-way clutch or the rolling bearings, for example,on a housing disposed radially outside the output rotating body or theinput rotating body for housing the one-way clutch or the rollingbearings. It is determined whether or not an abnormality possiblycausing a failure or the like has occurred by inputting a detectionvalue of the state monitoring sensor to the control unit for comparingthe detection value with a prescribed threshold value, and if it isdetermined that the abnormality has occurred, the control for stoppingthe power generator is executed. Besides, the detection means may be astate monitoring sensor provided on a bearing or a gear used within thespeed-up gear, the blade of the wind turbine, a bearing supporting themain shaft, or the like.

Regarding the first aspect of the present invention, the inventors ofthe present application made earnest studies on the occurrence mechanismof the smearing. As a result, the following was found, based on whichthe present invention was accomplished: When the rotational speed of themain shaft is abruptly lowered due to the lowering of the wind force,what is called a leak of torque (a leak of load) is caused because therotational speed of the drive shaft of the power generator exceeds therotational speed of the output shaft owing to the inertia of the rotorof the power generator having a large weight. This leak of torquereduces the radial load applied to the rolling bearing supporting theoutput shaft, and hence the sliding frictional resistance and the likebetween the rolling element of the rolling bearing and the cage holdingthe rolling element becomes larger than the rolling frictionalresistance between the rolling element and the turning wheel, and as aresult, the rotation of the rolling element is delayed. When therotational speed of the main shaft is abruptly increased from this statedue to the increase of the wind force, an inertia torque of the speedincrease is applied to increase the radial load applied to the rollingbearing supporting the output shaft. Therefore, the rolling elementslides on the contact surface in contact with the turning wheel with thehigh load applied to the rolling element at this point, which increasesthe temperature of the contact surface, and this is the cause of thesmearing.

Specifically, the first aspect of the present invention provides a windpower generation device including: a wind receiving member whichreceives a wind force to rotate a main shaft; a speed-up gear whichincludes a rotation transmission mechanism which receives rotation ofthe main shaft to increase the rotation in speed, and a rolling bearingwhich rotatably supports an output shaft which outputs a running torqueof the rotation transmission mechanism; a power generator which includesan input shaft which rotates by receiving rotation of the output shaft,and which generates power in accordance with rotation of a rotor whichrotates integrally with the input shaft; an input rotating body which isintegrally rotatably provided on the output shaft; an output rotatingbody which is integrally rotatably provided on the input shaft and whichis coaxially disposed radially inside or radially outside the inputrotating body; and a one-way clutch which is disposed between the inputrotating body and the output rotating body, which integrally rotatablyconnects the input rotating body and the output rotating body to eachother in a state in which a rotational speed of the input rotating bodyexceeds a rotational speed of the output rotating body, and which breaksconnection between the input rotating body and the output rotating bodyin a state in which the rotational speed of the input rotating body islower than the rotational speed of the output rotating body, wherein theinput rotating body and the output rotating body are allowed torelatively move along an axial direction, and a maximum allowance ofmovement thereof is set to be larger than variation of a distance alongthe axial direction between the input shaft and the output shaft causedby state change.

In the wind power generation device having the aforementioned structure,when the rotational speed of the input rotating body exceeds therotational speed of the output rotating body, the input rotating bodyand the output rotating body can be integrally rotatably connected toeach other by the one-way clutch, and when the rotational speed of theinput rotating body is lower than the rotational speed of the outputrotating body, the connection between the input rotating body and theoutput rotating body can be broken. In other words, even when therotational speed of the output shaft is abruptly lowered via the mainshaft due to the lowering of the wind force, the inertial rotation ofthe rotor of the power generator can be prevented from being transmittedvia the input shaft to the output shaft. Therefore, the decrease of theradial load applied to the rolling bearing supporting the output shaftand the delay of the rotation of the rolling element accompanying thedecrease can be suppressed. Accordingly, if the rotational speed of themain shaft is abruptly increased from this state due to change of thewind force and hence a high load is applied to the rolling element ofthe rolling bearing, the rolling element is difficult to slide on thecontact surface in contact with the turning wheel, and thus, theoccurrence of the smearing in the rolling bearing can be effectivelysuppressed.

Besides, the input rotating body and the output rotating body areallowed to relatively move along the axial direction, and the maximumallowance of their movement is set to be larger than the variation ofthe distance along the axial direction between the input shaft and theoutput shaft caused by state change. Therefore, even if the input shaftand the output shaft expand or contract due to change of theenvironmental temperature of the wind power generation device or changeof the temperature within the nacelle, the input rotating body and theoutput rotating body relatively move in accordance with the expansion orcontraction, so that occurrence of a load along the axial direction toany of the input shaft, the output shaft and members supporting theseshafts can be suppressed.

Preferably, the one-way clutch includes: an inner ring outercircumferential surface provided on a side of one rotating body out ofthe input rotating body and the output rotating body; an outer ringinner circumferential surface provided on a side of the other rotatingbody and disposed radially outside the inner ring outer circumferentialsurface; and a plurality of engaging elements disposed along acircumferential direction at intervals in a space formed between theinner ring outer circumferential surface and the outer ring innercircumferential surface, the input rotating body and the output rotatingbody are integrally rotatably connected to each other when the engagingelements engaged with the inner ring outer circumferential surface andthe outer ring inner circumferential surface, and the connection isbroken when the engagement therebetween is released, and a cylindricalroller bearing which relatively rotatably supports the input rotatingbody and the output rotating body is provided between the input rotatingbody and the output rotating body.

In this case, when the engagement between the engaging elements of theone-way clutch and the inner ring outer circumferential surface and theouter ring inner circumferential surface is released, the relativemovement along the radial direction of the input rotating body and theoutput rotating body against each other due to a gap caused therebetweencan be prevented by a second rolling bearing. Accordingly, during theoperation of the wind power generation device, the input rotating bodyand the output rotating body can be prevented from wobbling along theradial direction.

Preferably, the inner ring outer circumferential surface and the outerring inner circumferential surface are formed as cylindrical surfaces,and the engaging elements are formed by sprags.

If a sprag is used as each engaging element, both the inner ring outercircumferential surface and the outer ring inner circumferential surfacecan be formed as cylindrical surfaces, and hence, the inner ring outercircumferential surface and the outer ring inner circumferential surfacecan be easily formed. Besides, the torque capacity can be more easilyincreased by increasing the rigidity in using the sprag than in using aroller as the engaging element, and therefore, the dimensions along theradial direction and the axial direction of the sprag can be reduced. Asa result, the dimension of the other rotating body having the outer ringcircumferential surface can be reduced, so that the one-way clutch 7 canbe made compact.

Furthermore, if the engaging element is formed by a sprag, the innerring outer circumferential surface is preferably formed by an outercircumferential surface of one rotating body disposed radially inside,out of the input rotating body and the output rotating body. When thisstructure is employed, there is no need to provide an inner ring or thelike having an inner ring outer circumferential surface separately fromthe one rotating body, and hence, the one-way clutch can be made morecompact along the radial direction.

However, each of the engaging elements may be formed by a cylindricalroller disposed in each of a plurality of wedge-shaped spaces formedbetween the inner ring outer circumferential surface and the outer ringinner circumferential surface.

Preferably, an inner circumferential surface of one rotating bodydisposed radially outside, out of the input rotating body and the outputrotating body, is formed as a cylindrical surface, and configures theouter ring inner circumferential surface and an outer ring racewaysurface.

When this structure is employed, since the inner circumferential surfaceof the one rotating body configures the outer ring inner circumferentialsurface and the outer ring raceway surface, this one rotating body canbe used both as an outer ring having the outer ring innercircumferential surface and an outer ring having the outer ring racewaysurface, and hence, the structures of the one-way clutch and the secondrolling bearing can be simplified. Besides, when the innercircumferential surface of one of the rotating body is formed as acylindrical surface having a prescribed inner diameter, the rotatingbody can be moved along the axial direction against the engaging elementand the roller. Accordingly, the relative positions along the axialdirection of the input rotating body and the output rotating body can beadjusted in accordance with the distance along the axial directionbetween the output shaft and the input shaft, and the like.

Preferably, the input rotating body and the output rotating body form ashaft coupling device which integrally rotatably connects the outputshaft and the input shaft to each other, and the one-way clutch isincorporated in the shaft coupling device.

When this structure is employed, even if a space between the outputshaft and the input shaft is small, the one-way clutch can be suitablyprovided by utilizing the shaft coupling device connecting the outputshaft and the input shaft to each other.

Next, regarding the second and third aspects of the present invention,if a one-way clutch includes a rotating body provided on a side of anoutput shaft of a speed-up gear or on a side of an input shaft of apower generator, a ring fit on the rotating body, and an engagingelement to be engaged with the ring, in order to perform powertransmission from the rotating body to the ring by using a frictionalforce working therebetween, it is necessary to connect them by theinterference fit. In this case, if the power transmission therebetweenis performed merely by using the frictional force obtained by theinterference fit when a load for operating the power generator ismaximum, it is necessary to set an interference between a rotationalshaft and the ring extremely large, which excessively increases internalstress caused in the ring, and as a result, the lifetime of the ring,and the lifetime of the one-way clutch in the end is reduced.

Incidentally, a rotating body provided on a side of an output shaft of aspeed-up gear or on a side of an input shaft of a power generator in awind power generation device has a very large size, it is difficult todirectly machine the rotating body for obtaining a one-way clutch.Therefore, a ring separately processed is mounted to the rotating bodyin general, and therefore, it is extremely significant to solve theaforementioned problem.

The second and third aspects of the present invention were accomplishedin consideration of, for example, such an actual situation, and anobject is to provide a wind power generation device in which thelifetime of a one-way clutch provided between an output shaft of aspeed-up gear and an input shaft (a drive shaft) of a power generatorcan be increased.

The second aspect of the present invention provides a wind powergeneration device including: a speed-up gear which increases a speed ofrotation of a main shaft caused by a wind force to output the rotationincreased in speed from an output shaft; a power generator whichincludes an input shaft which rotates by receiving the rotation of theoutput shaft, and which generates power in accordance with rotation of arotor which rotates integrally with the input shaft; and a one-wayclutch which is provided between the output shaft and the input shaft,which integrally rotatably connects the output shaft and the input shaftto each other in a state in which a rotational speed of the output shaftexceeds a rotational speed of the input shaft, and which breaksconnection between the output shaft and the input shaft in a state inwhich the rotational speed of the output shaft is lower than therotational speed of the input shaft, wherein the one-way clutchincludes: a ring which is fit on a rotating body which rotates with theoutput shaft; another circumferential surface which is disposed tooppose outside or inside of a circumferential surface of the ring in aradial direction and which is provided on a side of the input shaft; anda plurality of engaging elements disposed in a space between thecircumferential surfaces, wherein the output shaft and the input shaftare integrally rotatably connected to each other by causing the engagingelements to engage the circumferential surfaces, and the connection isbroken by releasing the engagement therebetween, wherein a maximumtransmission torque T1 max to be transmitted from the rotating body tothe ring when a load torque for operating the power generator is maximumand a transmission torque T2 which can be transmitted from the rotatingbody to the ring with a tightening force obtained by fitting the ring onthe rotating body satisfy a relationship of T1max>T2, and wherein anecessary minimum transmission torque T1 to be transmitted from therotating body to the ring for operating the power generator, atransmission torque T3 which can be transmitted from the rotating bodyto the ring with a tightening force obtained by engagement of theengaging elements with the circumferential surfaces, and thetransmission torque T2 satisfy a relationship of T1<T2+T3.

Besides, the third aspect of the present invention provides a wind powergeneration device including: a speed-up gear which increases a speed ofrotation of a main shaft caused by a wind force to output the rotationincreased in speed from an output shaft; a power generator whichincludes an input shaft which rotates by receiving the rotation of theoutput shaft, and which generates power in accordance with rotation of arotor which rotates integrally with the input shaft; and a one-wayclutch which is provided between the output shaft and the input shaft,which integrally rotatably connects the output shaft and the input shaftto each other in a state in which a rotational speed of the output shaftexceeds a rotational speed of the input shaft, and which breaksconnection between the output shaft and the input shaft in a state inwhich the rotational speed of the output shaft is lower than therotational speed of the input shaft, wherein the one-way clutchincludes: a ring which is fit on a rotating body which rotates with theinput shaft; another circumferential surface disposed to oppose outsideor inside a circumferential surface of the ring in a radial directionand which is provided on a side of the output shaft; and a plurality ofengaging elements disposed in a space between the circumferentialsurfaces, wherein the output shaft and the input shaft are integrallyrotatably connected to each other by causing the engaging elements toengage the circumferential surfaces, and the connection is broken byreleasing the engagement therebetween, wherein a maximum transmissiontorque T1max to be transmitted from the rotating body to the ring when aload torque for operating the power generator is maximum and atransmission torque T2 which can be transmitted from the rotating bodyto the ring with a tightening force obtained by fitting the ring on therotating body satisfy a relationship of T1max>T2, and wherein anecessary minimum transmission torque T1 to be transmitted from therotating body to the ring for operating the power generator, atransmission torque T3 which can be transmitted from the rotating bodyto the ring with a tightening force obtained by engagement of theengaging elements with the circumferential surfaces, and thetransmission torque T2 satisfy a relationship of T1<T2+T3.

When these structures are employed, in consideration of not only thetightening force caused by the fitting between the rotating body and thering (the initial tightening force) but also the tightening force causedby the engagement between the ring and the engaging elements (theadditional tightening force), the transmission torque between therotating body and the ring is set to satisfy the necessary minimumtransmission torque for operating the power generator. Therefore, thereis no need to excessively increase the initial tightening force, andstress caused in the ring can be reduced as much as possible.Accordingly, the lifetime of the ring, and the lifetime of the one-wayclutch in the end can be increased.

Incidentally, an interference between the rotating body and the ring ispreferably equal to or larger than 10 μm. Thus, the transmission torquebetween the ring and the rotating body can be sufficiently secured at aninitial stage of the engagement between the engaging elements and thering.

Besides, the engaging elements are preferably provided in number of fourto eight arranged along a circumferential direction.

If the number of engaging elements exceeds eight, a force applied fromthe engaging elements to the circumferential surface of the ring isdispersed, and hence the tightening force obtained by the engagementtherebetween is reduced, and as a result, the transmission torque T3 isdifficult to sufficiently secure. If the number of engaging elements issmaller than four, the transmission torque T3 becomes too large on thecontrary, and there is a possibility that a burden to the ring may beincreased.

The one-way clutch is preferably incorporated in a shaft coupling devicewhich integrally rotatably connects the output shaft and the input shaftto each other.

When this structure is employed, even if a space along the axialdirection cannot be secured between the output shaft of the speed-upgear and the input shaft of the power generator, the one-way clutch canbe provided by utilizing the shaft coupling device for connecting theshafts to each other.

According to the second or third aspect of the present invention, thelifetime of the one-way clutch provided, for example, between the outputshaft of the speed-up gear and the input shaft of the power generatorcan be increased.

Next, regarding the fourth aspect of the present invention, a wind powergeneration device is generally installed in an environment where astrong wind force can be obtained and little influence of noise or thelike is given, such as on the coast or offshore. On the coast or thelike, however, the wind power generation device is exposed to an airflow containing a large amount of a salt content, and hence, it isnecessary to take measures against a salt damage. In particular, in acase where a one-way clutch is provided between a speed-up gear and apower generator, if metal corrosion or the like is caused by the saltdamage, transmission/non-transmission (connection/disconnection) of thepower between an output shaft and a drive shaft cannot be properlyperformed, which harmfully affects power generation efficiency and thelike.

An object of the fourth aspect of the present invention is to provide awind power generation device in which the function of a one-way clutchconnecting an output shaft of a speed-up gear and an input shaft (adrive shaft) of a power generator to each other cannot be impaired byinfluence of an ambient environment.

The fourth aspect of the present invention provides a wind powergeneration device including: a main shaft which rotates by a wind force;a speed-up gear which increases a speed of rotation of the main shaftand which outputs the rotation increased in speed from an output shaft;a power generator which includes an input shaft rotated by receiving therotation of the output shaft and which generates power in accordancewith rotation of a rotor which rotates integrally with the input shaft;a casing which houses the speed-up gear and the power generator; aninput rotating body which is integrally rotatably provided on the outputshaft; an output rotating body which is integrally rotatably provided onthe input shaft and which is disposed coaxially radially inside orradially outside the input rotating body; a one-way clutch which isdisposed between the input rotating body and the output rotating body,which integrally rotatably connects the input rotating body and theoutput rotating body to each other in a state in which a rotationalspeed of the input rotating body exceeds a rotational speed of theoutput rotating body, and which breaks connection between the inputrotating body and the output rotating body in a state in which therotational speed of the input rotating body is lower than the rotationalspeed of the output rotating body; and shielding means which shields aregion where the one-way clutch is disposed from a space within thecasing.

In the wind power generation device according to the fourth aspect ofthe present invention, the one-way clutch is provided between the outputshaft of the speed-up gear and the input shaft of the power generator,and the shielding means for sealing the region where this one-way clutchis disposed from its surrounding space, that is, the space within thecasing, is provided. Therefore, the shielding means inhibits a foreignmatter, an air flow or the like from entering the region where theone-way clutch is disposed, and hence the one-way clutch is difficult tobe affected by a salt damage or the like, and as a result, the functionof the one-way clutch, such as the transmission/non-transmission of thepower between the output shaft and the input shaft, can be suitablyretained. Incidentally, the region where the one-way clutch is disposedrefers to a portion where the one-way clutch is disposed within a rangewhere the input rotating body and the output rotating body oppose eachother along the radial direction.

Preferably, the shielding means includes a covering member covering theinput rotating body and the output rotating body from outside along theradial direction, and the covering member is relatively unrotatablyconnected to one of the input rotating body and the output rotating bodyand relatively rotatably connected to the other.

When this structure is employed, even if the connection between theoutput shaft and the input shaft is broken by the one-way clutch andthese shafts are relatively rotated against each other, the coveringmember can follow the rotation.

The covering member is preferably expandable/contractible along theaxial direction. When this structure is employed, the covering membercan be caused to follow variation of a distance along the axialdirection of the output shaft and the input shaft, or the like.

Preferably, the input rotating body and the output rotating body areincluded in a shaft coupling device that integrally rotatably connectsthe output shaft and the input shaft to each other, and the one-wayclutch is incorporated in the shaft coupling device.

When the one-way clutch is incorporated in the shaft coupling deviceconnecting the output shaft and the input shaft to each other, even ifthe distance along the axial direction between these shafts is too smallto secure a space where the one-way clutch is singly disposed, theone-way clutch can be provided between these shafts together with theshaft coupling device.

In the wind power generation device according to the fourth aspect ofthe present invention, the one-way clutch provided, for example, betweenthe output shaft of the speed-up gear and the input shaft of the powergenerator is difficult to be affected by a salt damage or the like, andthe function of the one-way clutch can be suitably retained.

Next, regarding the fifth aspect of the present invention, if it isdesired to stop a power generator because of a failure or an accident ofthe power generator, or because of maintenance or the like, a windturbine is generally stopped by changing the direction (the pitch angle)of a blade of the wind turbine to place it in a state where a wind forceis not applied. If the one-way clutch is provided between the outputshaft of the speed-up gear and the drive shaft of the power generator asdescribed above, however, even though the output shaft of the speed-upgear is stopped by stopping the wind turbine, the drive shaft of thepower generator continuously rotates due to inertia of the rotor, andhence, the power generator cannot be rapidly stopped.

Accordingly, an object of the fifth aspect of the present invention is,in consideration of the aforementioned circumstances, to provide a powergeneration device in which a power generator can be rapidly stopped bystopping supply of an external force even if a one-way clutch isprovided between an output shaft of a reduction gear and a drive shaftof the power generator.

The fifth aspect of the present invention provides a power generationdevice including: a main shaft which rotates by an external force; aspeed-up gear which increases a speed of rotation received from the mainshaft and which outputs the rotation increased in speed from an outputshaft; a power generator which includes a drive shaft which rotates byreceiving the rotation of the output shaft and a rotor which rotatesintegrally with the drive shaft, and which generates power in accordancewith the rotation of the rotor; a one-way clutch which is providedbetween the output shaft and the drive shaft, which integrally rotatablyconnects the output shaft and the drive shaft to each other in a firststate in which a rotational speed of the output shaft exceeds arotational speed of the drive shaft, and which breaks connection betweenthe output shaft and the drive shaft in a second state in which therotational speed of the output shaft is lower than the rotational speedof the drive shaft; connecting means which is provided between theoutput shaft and the drive shaft and which is capable of integrallyrotatably connecting the output shaft and the drive shaft to each otherat least in the second state; and a control unit which controls anoperation of the connecting means to connect the output shaft and thedrive shaft to each other in accordance with a prescribed condition.

In the power generation device according to the fifth aspect of thepresent invention, the one-way clutch is provided between the outputshaft of the speed-up gear and the drive shaft of the power generator,and in the state where the rotation of the output shaft exceeds therotational speed of the drive shaft (in the first state), the rotationof the output shaft can be suitably transmitted to the drive shaft, soas to operate the power generator. On the contrary, in the state wherethe rotation of the output shaft is lower than the rotational speed ofthe drive shaft (in the second state), the rotation of the output shaftis not transmitted to the drive shaft so as to prevent the rotationalspeed of the drive shaft from being lowered, and the rotor of the powergenerator can be rotated by inertia. Therefore, the lowering of anaverage rotational speed of the power generator and the lowering ofpower generation efficiency can be suppressed.

On the other hand, when the supply of the external force (such as arotational force from a wind turbine) is stopped for stopping the powergenerator, the rotation of the output shaft of the speed-up gear isabruptly lowered in speed to stop, and hence the second state isattained and the one-way clutch breaks the connection between the outputshaft and the drive shaft. Accordingly, if it is left in this state, thedrive shaft continuously rotates due to the inertia of the rotor, andthe power generator cannot be rapidly stopped. In the power generationdevice of the present invention, however, in addition to the one-wayclutch, the connecting means capable of integrally rotatably connectingthe output shaft and the drive shaft to each other at least in thesecond state is provided, and this connecting means is controlled by thecontrol unit to connect the output shaft and the drive shaft to eachother in accordance with the prescribed condition. Therefore, if it isdesired to stop the power generator, the output shaft and the driveshaft are connected to each other by the connecting means to cause thespeed-up gear to work as a brake, and thus, the rotation of the driveshaft can be abruptly lowered in speed so as to rapidly stop the powergenerator.

Preferably, the speed-up gear includes: a rotation transmissionmechanism for increasing the speed of the rotation of the main shaft;the output shaft for outputting the rotation increased in speed by therotation transmission mechanism; and a roller bearing rotatablysupporting the output shaft, an input rotating body is integrallyrotatably provided on the output shaft, an output rotating body disposedcoaxially radially inside or radially outside the input rotating body isintegrally rotatably provided on the drive shaft, and the one-way clutchis disposed between the input rotating body and the output rotatingbody.

Since the conventional technique described above (FIG. 23, PatentDocument 1) has the problem in which the lifetime is reduced because ofthe smearing occurring in the roller bearing, the inventors of thepresent application made earnest studies on the occurrence mechanism ofthe smearing. As a result, the following was found: When the rotationalspeed of the main shaft is abruptly lowered due to the lowering of thewind force, what is called a leak of torque (a leak of load) is causedbecause the rotational speed of the drive shaft of the power generatorexceeds the rotational speed of the output shaft owing to the inertia ofthe rotor of the power generator having a large weight. This leak oftorque reduces the radial load applied to the rolling bearing supportingthe output shaft, and hence the sliding frictional resistance and thelike between the roller of the roller bearing and the cage holding therotor becomes larger than the rolling frictional resistance between theroller and the turning wheel, and as a result, the rotation of theroller is delayed. When the rotational speed of the main shaft isabruptly increased from this state due to the increase of the windforce, an inertia torque of the speed increase is applied to increasethe radial load applied to the roller bearing supporting the outputshaft. Therefore, the roller slides on the contact surface in contactwith the turning wheel with the high load applied to the roller at thispoint, which increases the temperature of the contact surface, and thisis the cause of the smearing.

In the fifth aspect of the present invention, owing to the one-wayclutch, if the rotational speed of the input rotating body exceeds therotational speed of the output rotating body, the input rotating bodyand the output rotating body can be integrally rotatably connected toeach other, and if the rotational speed of the input rotating body islower than the rotational speed of the output rotating body, theconnection between the input rotating body and the output rotating bodycan be broken. In other words, even when the rotational speed of theoutput shaft is abruptly lowered via the main shaft due to the loweringof the external force, the inertial rotation of the rotor of the powergenerator can be prevented from being transmitted via the drive shaft tothe output shaft. Therefore, the decrease of the radial load applied tothe roller bearing supporting the output shaft and the delay of therotation of the roller accompanying the decrease can be suppressed.Accordingly, if the rotational speed of the main shaft is abruptlyincreased from this state due to change of the external force and hencea high load is applied to the roller, the roller is difficult to slideon the contact surface in contact with the turning wheel, and thus, theoccurrence of the smearing in the roller bearing can be effectivelysuppressed.

The prescribed condition is preferably a condition for stopping thepower generator.

If the output shaft and the drive shaft are connected to each other whenthe condition for stopping the power generator is satisfied, the powergenerator can be rapidly stopped.

Besides, the power generation device according to the fifth aspect ofthe present invention preferably includes detection means for detectinga state of the power generation device, and the control unit preferablycontrols the connecting means on the basis of a detection resultobtained by the detection means.

If the power generator has a problem of a failure or an accident,various states of the power generation device are changed. Therefore,the problem of the power generator can be discovered at an early stageby detecting the states of the power generation device by the detectionmeans, and the power generator can be rapidly and automatically stopped.

The detection means may include a temperature sensor for detecting atemperature of the power generator.

If the temperature of the power generator is abnormally increased, itcan be regarded that there is a possibility of a problem such as aseizure having occurred in the power generator. Therefore, if thetemperature sensor is provided as the detection means, this problem canbe discovered at an early stage, and the power generator can be rapidlystopped.

The detection means may include a vibration sensor for detectingvibration of the power generator.

If the vibration of the power generator is abnormally increased, it canbe regarded that there is a possibility of a problem such as a damagehaving occurred in a shaft or a bearing included therein. Therefore, ifthe vibration sensor is provided as the detection means, this problemcan be discovered at an early stage, and the power generator can berapidly stopped.

The detection means may include a speed sensor for detecting therotational speed of the output shaft, the drive shaft or the main shaft,and a power generation measuring device for detecting an amount of powergenerated by the power generator.

Since there is a correlation between the rotational speed of the outputshaft, the drive shaft or the main shaft and the amount of powergenerated by the power generator, for example, if the amount ofgenerated power is small although the rotational speed of the shaft islarge, it can be regarded that there is a possibility of any problemhaving occurred in the power generator. Therefore, if the speed sensorand the power generation measuring device are provided as the detectionmeans, this problem can be discovered at an early stage, and the powergenerator can be rapidly stopped.

The power generation device according to the fifth aspect of the presentinvention may include accepting means for accepting an input of afactitious stop instruction for the power generator, and the controlunit may control the connecting means on the basis of whether or not theaccepting means has accepted the stop instruction.

When this structure is employed, if, for example, it is desired tofactitiously stop the power generator for maintenance or the like, thepower generator can be rapidly stopped by inputting a stop instructionto the accepting means.

In the aforementioned structure, the one-way clutch and the connectingmeans are preferably disposed coaxially with the output shaft and thedrive shaft.

When this structure is employed, the one-way clutch and the connectingmeans can be disposed compactly.

Besides, the connecting means is preferably an electromagnetic clutch.

When this structure is employed, the connection/disconnection betweenthe output shaft and the drive shaft can be rapidly and accuratelyperformed.

In the power generation device according to the fifth aspect of thepresent invention, the power generator can be rapidly stopped bystopping the supply of the external force even if the one-way clutch isprovided between the output shaft of the reduction gear and the driveshaft of the power generator.

The present application is based upon the Japanese patent application(Japanese Patent Application No. 2013-048593) filed on Mar. 12, 2013,the Japanese patent application (Japanese Patent Application No.2013-048618) filed on Mar. 12, 2013, the Japanese patent application(Japanese Patent Application No. 2013-048628) filed on Mar. 12, 2013,and the Japanese patent application (Japanese Patent Application No.2013-048642) filed on Mar. 12, 2013, the entire contents of which areincorporated herein by reference.

DESCRIPTION OF REFERENCE SIGNS

1: wind power generation device, 2: main shaft, 3: speed-up gear, 4:power generator, 5, 105: input rotating body (inside rotating body), 6,106: output rotating body (outside rotating body), 7, 107: one-wayclutch, 8, 108: rolling bearing (cylindrical roller bearing), 9, 109:shaft coupling device, 11: blade (wind receiving member), 30: gearmechanism (rotation transmission mechanism), 35: output shaft, 38:roller bearing, 41: drive shaft, 42: rotor, 71: inner ring (ring), 71 a:outer circumferential surface (inner ring outer circumferentialsurface), 72 a: inner circumferential surface (outer ring innercircumferential surface), 73: engaging element (roller, sprag), 74:cage, 81 b: inner ring flange portion, 82 a: outer ring raceway surface,83: cylindrical roller, 92: covering member (shielding means), S:wedge-shaped space, 112: control unit, 121: temperature sensor, 122:vibration sensor, 123: speed sensor, 124: power generation measuringdevice, 125: stop switch (accepting means)

The invention claimed is:
 1. A wind power generation device comprising:a wind receiving member which receives a wind force to rotate a mainshaft; a speed-up gear which comprises a rotation transmission mechanismwhich receives rotation of the main shaft to increase the rotation inspeed, and a rolling bearing which rotatably supports an output shaftwhich outputs a running torque of the rotation transmission mechanism; apower generator which comprises an input shaft which rotates byreceiving rotation of the output shaft, and which generates power inaccordance with rotation of a rotor which rotates integrally with theinput shaft; an input rotating body which is integrally rotatablyprovided on the output shaft; an output rotating body which isintegrally rotatably provided on the input shaft and which is coaxiallydisposed radially inside or radially outside the input rotating body;and a one-way clutch which is disposed between the input rotating bodyand the output rotating body, which integrally rotatably connects theinput rotating body and the output rotating body to each other in astate in which a rotational speed of the input rotating body exceeds arotational speed of the output rotating body, and which breaksconnection between the input rotating body and the output rotating bodyin a state in which the rotational speed of the input rotating body islower than the rotational speed of the output rotating body, wherein theinput rotating body and the output rotating body are allowed torelatively move along an axial direction, and a maximum allowance ofmovement thereof is set to be larger than variation of a distance alongthe axial direction between the input shaft and the output shaft causedby state change.
 2. The wind power generation device according to claim1, wherein the one-way clutch comprises an inner ring outercircumferential surface provided on a side of one rotating body out ofthe input rotating body and the output rotating body; an outer ringinner circumferential surface provided on a side of the other rotatingbody and disposed radially outside the inner ring outer circumferentialsurface; and a plurality of engaging elements disposed along acircumferential direction at intervals in a space formed between theinner ring outer circumferential surface and the outer ring innercircumferential surface, wherein the input rotating body and the outputrotating body are integrally rotatably connected to each other when theengaging elements engaged with the inner ring outer circumferentialsurface and the outer ring inner circumferential surface, and theconnection is broken when the engagement therebetween is released, andwherein a cylindrical roller bearing which relatively rotatably supportsthe input rotating body and the output rotating body is provided betweenthe input rotating body and the output rotating body.
 3. The wind powergeneration device according to claim 2, wherein the inner ring outercircumferential surface and the outer ring inner circumferential surfaceare formed as cylindrical surfaces, and the engaging elements are formedby sprags.
 4. The wind power generation device according to claim 3,wherein the inner ring outer circumferential surface is formed by anouter circumferential surface of one rotating body disposed radiallyinside, out of the input rotating body and the output rotating body. 5.The wind power generation device according to claim 2, wherein aplurality of wedge-shaped spaces are formed between the inner ring outercircumferential surface and the outer ring inner circumferentialsurface, and each of the engaging elements is formed by a cylindricalroller disposed in each of the wedge-shaped spaces.
 6. The wind powergeneration device according to claim 2, wherein an inner circumferentialsurface of one rotating body disposed radially outside, out of the inputrotating body and the output rotating body, is formed as a cylindricalsurface, and configures the outer ring inner circumferential surface andan outer ring raceway surface.
 7. The wind power generation deviceaccording to claim 1, wherein the input rotating body and the outputrotating body form a shaft coupling device which integrally rotatablyconnects the output shaft and the input shaft to each other, and theone-way clutch is incorporated in the shaft coupling device.